#pragma once

// CLI11: Version 1.8.0
// Originally designed by Henry Schreiner
// https://github.com/CLIUtils/CLI11
//
// This is a standalone header file generated by MakeSingleHeader.py in CLI11/scripts
// from: v1.8.0
//
// From LICENSE:
//
// CLI11 1.8 Copyright (c) 2017-2019 University of Cincinnati, developed by Henry
// Schreiner under NSF AWARD 1414736. All rights reserved.
//
// Redistribution and use in source and binary forms of CLI11, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
// 3. Neither the name of the copyright holder nor the names of its contributors
//    may be used to endorse or promote products derived from this software without
//    specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
// ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// Standard combined includes:

#include <algorithm>
#include <cmath>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <istream>
#include <iterator>
#include <locale>
#include <map>
#include <memory>
#include <numeric>
#include <set>
#include <sstream>
#include <stdexcept>
#include <string>
#include <sys/stat.h>
#include <sys/types.h>
#include <tuple>
#include <type_traits>
#include <utility>
#include <vector>

// Verbatim copy from CLI/Version.hpp:

#define CLI11_VERSION_MAJOR 1
#define CLI11_VERSION_MINOR 8
#define CLI11_VERSION_PATCH 0
#define CLI11_VERSION "1.8.0"

// Verbatim copy from CLI/Macros.hpp:

// The following version macro is very similar to the one in PyBind11
#if !(defined(_MSC_VER) && __cplusplus == 199711L) && !defined(__INTEL_COMPILER)
#if __cplusplus >= 201402L
#define CLI11_CPP14
#if __cplusplus >= 201703L
#define CLI11_CPP17
#if __cplusplus > 201703L
#define CLI11_CPP20
#endif
#endif
#endif
#elif defined(_MSC_VER) && __cplusplus == 199711L
// MSVC sets _MSVC_LANG rather than __cplusplus (supposedly until the standard is fully implemented)
// Unless you use the /Zc:__cplusplus flag on Visual Studio 2017 15.7 Preview 3 or newer
#if _MSVC_LANG >= 201402L
#define CLI11_CPP14
#if _MSVC_LANG > 201402L && _MSC_VER >= 1910
#define CLI11_CPP17
#if __MSVC_LANG > 201703L && _MSC_VER >= 1910
#define CLI11_CPP20
#endif
#endif
#endif
#endif

#if defined(CLI11_CPP14)
#define CLI11_DEPRECATED(reason) [[deprecated(reason)]]
#elif defined(_MSC_VER)
#define CLI11_DEPRECATED(reason) __declspec(deprecated(reason))
#else
#define CLI11_DEPRECATED(reason) __attribute__((deprecated(reason)))
#endif

// Verbatim copy from CLI/Optional.hpp:

// You can explicitly enable or disable support
// by defining to 1 or 0. Extra check here to ensure it's in the stdlib too.
// We nest the check for __has_include and it's usage
#ifndef CLI11_STD_OPTIONAL
#ifdef __has_include
#if defined(CLI11_CPP17) && __has_include(<optional>)
#define CLI11_STD_OPTIONAL 1
#else
#define CLI11_STD_OPTIONAL 0
#endif
#else
#define CLI11_STD_OPTIONAL 0
#endif
#endif

#ifndef CLI11_EXPERIMENTAL_OPTIONAL
#define CLI11_EXPERIMENTAL_OPTIONAL 0
#endif

#ifndef CLI11_BOOST_OPTIONAL
#define CLI11_BOOST_OPTIONAL 0
#endif

#if CLI11_BOOST_OPTIONAL
#include <boost/version.hpp>
#if BOOST_VERSION < 106100
#error "This boost::optional version is not supported, use 1.61 or better"
#endif
#endif

#if CLI11_STD_OPTIONAL
#include <optional>
#endif
#if CLI11_EXPERIMENTAL_OPTIONAL
#include <experimental/optional>
#endif
#if CLI11_BOOST_OPTIONAL
#include <boost/optional.hpp>
#include <boost/optional/optional_io.hpp>
#endif

// From CLI/Version.hpp:

// From CLI/Macros.hpp:

// From CLI/Optional.hpp:

namespace CLI
{
#if CLI11_STD_OPTIONAL
    template<typename T>
    std::istream& operator>>(std::istream& in, std::optional<T>& val)
    {
        T v;
        in >> v;
        val = v;
        return in;
    }
#endif

#if CLI11_EXPERIMENTAL_OPTIONAL
    template<typename T>
    std::istream& operator>>(std::istream& in, std::experimental::optional<T>& val)
    {
        T v;
        in >> v;
        val = v;
        return in;
    }
#endif

#if CLI11_BOOST_OPTIONAL
    template<typename T>
    std::istream& operator>>(std::istream& in, boost::optional<T>& val)
    {
        T v;
        in >> v;
        val = v;
        return in;
    }
#endif

// Export the best optional to the CLI namespace
#if CLI11_STD_OPTIONAL
    using std::optional;
#elif CLI11_EXPERIMENTAL_OPTIONAL
    using std::experimental::optional;
#elif CLI11_BOOST_OPTIONAL
    using boost::optional;
#endif

// This is true if any optional is found
#if CLI11_STD_OPTIONAL || CLI11_EXPERIMENTAL_OPTIONAL || CLI11_BOOST_OPTIONAL
#define CLI11_OPTIONAL 1
#endif

} // namespace CLI

// From CLI/StringTools.hpp:

namespace CLI
{
    /// Include the items in this namespace to get free conversion of enums to/from streams.
    /// (This is available inside CLI as well, so CLI11 will use this without a using statement).
    namespace enums
    {
        /// output streaming for enumerations
        template<typename T, typename = typename std::enable_if<std::is_enum<T>::value>::type>
        std::ostream& operator<<(std::ostream& in, const T& item)
        {
            // make sure this is out of the detail namespace otherwise it won't be found when needed
            return in << static_cast<typename std::underlying_type<T>::type>(item);
        }

        /// input streaming for enumerations
        template<typename T, typename = typename std::enable_if<std::is_enum<T>::value>::type>
        std::istream& operator>>(std::istream& in, T& item)
        {
            typename std::underlying_type<T>::type i;
            in >> i;
            item = static_cast<T>(i);
            return in;
        }
    } // namespace enums

    /// Export to CLI namespace
    using namespace enums;

    namespace detail
    {
        // Based on http://stackoverflow.com/questions/236129/split-a-string-in-c
        /// Split a string by a delim
        inline std::vector<std::string> split(const std::string& s, char delim)
        {
            std::vector<std::string> elems;
            // Check to see if empty string, give consistent result
            if (s.empty())
                elems.emplace_back();
            else
            {
                std::stringstream ss;
                ss.str(s);
                std::string item;
                while (std::getline(ss, item, delim))
                {
                    elems.push_back(item);
                }
            }
            return elems;
        }
        /// simple utility to convert various types to a string
        template<typename T>
        inline std::string as_string(const T& v)
        {
            std::ostringstream s;
            s << v;
            return s.str();
        }
        // if the data type is already a string just forward it
        template<typename T, typename = typename std::enable_if<std::is_constructible<std::string, T>::value>::type>
        inline auto as_string(T&& v) -> decltype(std::forward<T>(v))
        {
            return std::forward<T>(v);
        }

        /// Simple function to join a string
        template<typename T>
        std::string join(const T& v, std::string delim = ",")
        {
            std::ostringstream s;
            auto beg = std::begin(v);
            auto end = std::end(v);
            if (beg != end)
                s << *beg++;
            while (beg != end)
            {
                s << delim << *beg++;
            }
            return s.str();
        }

        /// Simple function to join a string from processed elements
        template<typename T,
                 typename Callable,
                 typename = typename std::enable_if<!std::is_constructible<std::string, Callable>::value>::type>
        std::string join(const T& v, Callable func, std::string delim = ",")
        {
            std::ostringstream s;
            auto beg = std::begin(v);
            auto end = std::end(v);
            if (beg != end)
                s << func(*beg++);
            while (beg != end)
            {
                s << delim << func(*beg++);
            }
            return s.str();
        }

        /// Join a string in reverse order
        template<typename T>
        std::string rjoin(const T& v, std::string delim = ",")
        {
            std::ostringstream s;
            for (size_t start = 0; start < v.size(); start++)
            {
                if (start > 0)
                    s << delim;
                s << v[v.size() - start - 1];
            }
            return s.str();
        }

        // Based roughly on http://stackoverflow.com/questions/25829143/c-trim-whitespace-from-a-string

        /// Trim whitespace from left of string
        inline std::string& ltrim(std::string& str)
        {
            auto it = std::find_if(str.begin(), str.end(), [](char ch) { return !std::isspace<char>(ch, std::locale()); });
            str.erase(str.begin(), it);
            return str;
        }

        /// Trim anything from left of string
        inline std::string& ltrim(std::string& str, const std::string& filter)
        {
            auto it = std::find_if(str.begin(), str.end(), [&filter](char ch) { return filter.find(ch) == std::string::npos; });
            str.erase(str.begin(), it);
            return str;
        }

        /// Trim whitespace from right of string
        inline std::string& rtrim(std::string& str)
        {
            auto it = std::find_if(str.rbegin(), str.rend(), [](char ch) { return !std::isspace<char>(ch, std::locale()); });
            str.erase(it.base(), str.end());
            return str;
        }

        /// Trim anything from right of string
        inline std::string& rtrim(std::string& str, const std::string& filter)
        {
            auto it =
                std::find_if(str.rbegin(), str.rend(), [&filter](char ch) { return filter.find(ch) == std::string::npos; });
            str.erase(it.base(), str.end());
            return str;
        }

        /// Trim whitespace from string
        inline std::string& trim(std::string& str) { return ltrim(rtrim(str)); }

        /// Trim anything from string
        inline std::string& trim(std::string& str, const std::string filter) { return ltrim(rtrim(str, filter), filter); }

        /// Make a copy of the string and then trim it
        inline std::string trim_copy(const std::string& str)
        {
            std::string s = str;
            return trim(s);
        }

        /// Make a copy of the string and then trim it, any filter string can be used (any char in string is filtered)
        inline std::string trim_copy(const std::string& str, const std::string& filter)
        {
            std::string s = str;
            return trim(s, filter);
        }
        /// Print a two part "help" string
        inline std::ostream& format_help(std::ostream& out, std::string name, std::string description, size_t wid)
        {
            name = "  " + name;
            out << std::setw(static_cast<int>(wid)) << std::left << name;
            if (!description.empty())
            {
                if (name.length() >= wid)
                    out << "\n"
                        << std::setw(static_cast<int>(wid)) << "";
                for (const char c : description)
                {
                    out.put(c);
                    if (c == '\n')
                    {
                        out << std::setw(static_cast<int>(wid)) << "";
                    }
                }
            }
            out << "\n";
            return out;
        }

        /// Verify the first character of an option
        template<typename T>
        bool valid_first_char(T c)
        {
            return std::isalnum(c, std::locale()) || c == '_' || c == '?' || c == '@';
        }

        /// Verify following characters of an option
        template<typename T>
        bool valid_later_char(T c)
        {
            return valid_first_char(c) || c == '.' || c == '-';
        }

        /// Verify an option name
        inline bool valid_name_string(const std::string& str)
        {
            if (str.empty() || !valid_first_char(str[0]))
                return false;
            for (auto c : str.substr(1))
                if (!valid_later_char(c))
                    return false;
            return true;
        }

        /// Verify that str consists of letters only
        inline bool isalpha(const std::string& str)
        {
            return std::all_of(str.begin(), str.end(), [](char c) { return std::isalpha(c, std::locale()); });
        }

        /// Return a lower case version of a string
        inline std::string to_lower(std::string str)
        {
            std::transform(std::begin(str), std::end(str), std::begin(str), [](const std::string::value_type& x) {
                return std::tolower(x, std::locale());
            });
            return str;
        }

        /// remove underscores from a string
        inline std::string remove_underscore(std::string str)
        {
            str.erase(std::remove(std::begin(str), std::end(str), '_'), std::end(str));
            return str;
        }

        /// Find and replace a substring with another substring
        inline std::string find_and_replace(std::string str, std::string from, std::string to)
        {
            size_t start_pos = 0;

            while ((start_pos = str.find(from, start_pos)) != std::string::npos)
            {
                str.replace(start_pos, from.length(), to);
                start_pos += to.length();
            }

            return str;
        }

        /// check if the flag definitions has possible false flags
        inline bool has_default_flag_values(const std::string& flags)
        {
            return (flags.find_first_of("{!") != std::string::npos);
        }

        inline void remove_default_flag_values(std::string& flags)
        {
            auto loc = flags.find_first_of('{');
            while (loc != std::string::npos)
            {
                auto finish = flags.find_first_of("},", loc + 1);
                if ((finish != std::string::npos) && (flags[finish] == '}'))
                {
                    flags.erase(flags.begin() + static_cast<std::ptrdiff_t>(loc),
                                flags.begin() + static_cast<std::ptrdiff_t>(finish) + 1);
                }
                loc = flags.find_first_of('{', loc + 1);
            }
            flags.erase(std::remove(flags.begin(), flags.end(), '!'), flags.end());
        }

        /// Check if a string is a member of a list of strings and optionally ignore case or ignore underscores
        inline std::ptrdiff_t find_member(std::string name,
                                          const std::vector<std::string> names,
                                          bool ignore_case = false,
                                          bool ignore_underscore = false)
        {
            auto it = std::end(names);
            if (ignore_case)
            {
                if (ignore_underscore)
                {
                    name = detail::to_lower(detail::remove_underscore(name));
                    it = std::find_if(std::begin(names), std::end(names), [&name](std::string local_name) {
                        return detail::to_lower(detail::remove_underscore(local_name)) == name;
                    });
                }
                else
                {
                    name = detail::to_lower(name);
                    it = std::find_if(std::begin(names), std::end(names), [&name](std::string local_name) {
                        return detail::to_lower(local_name) == name;
                    });
                }
            }
            else if (ignore_underscore)
            {
                name = detail::remove_underscore(name);
                it = std::find_if(std::begin(names), std::end(names), [&name](std::string local_name) {
                    return detail::remove_underscore(local_name) == name;
                });
            }
            else
                it = std::find(std::begin(names), std::end(names), name);

            return (it != std::end(names)) ? (it - std::begin(names)) : (-1);
        }

        /// Find a trigger string and call a modify callable function that takes the current string and starting position of the
        /// trigger and returns the position in the string to search for the next trigger string
        template<typename Callable>
        inline std::string find_and_modify(std::string str, std::string trigger, Callable modify)
        {
            size_t start_pos = 0;
            while ((start_pos = str.find(trigger, start_pos)) != std::string::npos)
            {
                start_pos = modify(str, start_pos);
            }
            return str;
        }

        /// Split a string '"one two" "three"' into 'one two', 'three'
        /// Quote characters can be ` ' or "
        inline std::vector<std::string> split_up(std::string str)
        {
            const std::string delims("\'\"`");
            auto find_ws = [](char ch) { return std::isspace<char>(ch, std::locale()); };
            trim(str);

            std::vector<std::string> output;
            bool embeddedQuote = false;
            char keyChar = ' ';
            while (!str.empty())
            {
                if (delims.find_first_of(str[0]) != std::string::npos)
                {
                    keyChar = str[0];
                    auto end = str.find_first_of(keyChar, 1);
                    while ((end != std::string::npos) && (str[end - 1] == '\\'))
                    { // deal with escaped quotes
                        end = str.find_first_of(keyChar, end + 1);
                        embeddedQuote = true;
                    }
                    if (end != std::string::npos)
                    {
                        output.push_back(str.substr(1, end - 1));
                        str = str.substr(end + 1);
                    }
                    else
                    {
                        output.push_back(str.substr(1));
                        str = "";
                    }
                }
                else
                {
                    auto it = std::find_if(std::begin(str), std::end(str), find_ws);
                    if (it != std::end(str))
                    {
                        std::string value = std::string(str.begin(), it);
                        output.push_back(value);
                        str = std::string(it, str.end());
                    }
                    else
                    {
                        output.push_back(str);
                        str = "";
                    }
                }
                // transform any embedded quotes into the regular character
                if (embeddedQuote)
                {
                    output.back() = find_and_replace(output.back(), std::string("\\") + keyChar, std::string(1, keyChar));
                    embeddedQuote = false;
                }
                trim(str);
            }
            return output;
        }

        /// Add a leader to the beginning of all new lines (nothing is added
        /// at the start of the first line). `"; "` would be for ini files
        ///
        /// Can't use Regex, or this would be a subs.
        inline std::string fix_newlines(std::string leader, std::string input)
        {
            std::string::size_type n = 0;
            while (n != std::string::npos && n < input.size())
            {
                n = input.find('\n', n);
                if (n != std::string::npos)
                {
                    input = input.substr(0, n + 1) + leader + input.substr(n + 1);
                    n += leader.size();
                }
            }
            return input;
        }

        /// This function detects an equal or colon followed by an escaped quote after an argument
        /// then modifies the string to replace the equality with a space.  This is needed
        /// to allow the split up function to work properly and is intended to be used with the find_and_modify function
        /// the return value is the offset+1 which is required by the find_and_modify function.
        inline size_t escape_detect(std::string& str, size_t offset)
        {
            auto next = str[offset + 1];
            if ((next == '\"') || (next == '\'') || (next == '`'))
            {
                auto astart = str.find_last_of("-/ \"\'`", offset - 1);
                if (astart != std::string::npos)
                {
                    if (str[astart] == ((str[offset] == '=') ? '-' : '/'))
                        str[offset] = ' '; // interpret this as a space so the split_up works properly
                }
            }
            return offset + 1;
        }

        /// Add quotes if the string contains spaces
        inline std::string& add_quotes_if_needed(std::string& str)
        {
            if ((str.front() != '"' && str.front() != '\'') || str.front() != str.back())
            {
                char quote = str.find('"') < str.find('\'') ? '\'' : '"';
                if (str.find(' ') != std::string::npos)
                {
                    str.insert(0, 1, quote);
                    str.append(1, quote);
                }
            }
            return str;
        }

    } // namespace detail

} // namespace CLI

// From CLI/Error.hpp:

namespace CLI
{
// Use one of these on all error classes.
// These are temporary and are undef'd at the end of this file.
#define CLI11_ERROR_DEF(parent, name)                                                                                      \
protected:                                                                                                                 \
    name(std::string ename, std::string msg, int exit_code) : parent(std::move(ename), std::move(msg), exit_code) {}       \
    name(std::string ename, std::string msg, ExitCodes exit_code) : parent(std::move(ename), std::move(msg), exit_code) {} \
                                                                                                                           \
public:                                                                                                                    \
    name(std::string msg, ExitCodes exit_code) : parent(#name, std::move(msg), exit_code) {}                               \
    name(std::string msg, int exit_code) : parent(#name, std::move(msg), exit_code) {}

// This is added after the one above if a class is used directly and builds its own message
#define CLI11_ERROR_SIMPLE(name) \
    explicit name(std::string msg) : name(#name, msg, ExitCodes::name) {}

    /// These codes are part of every error in CLI. They can be obtained from e using e.exit_code or as a quick shortcut,
    /// int values from e.get_error_code().
    enum class ExitCodes
    {
        Success = 0,
        IncorrectConstruction = 100,
        BadNameString,
        OptionAlreadyAdded,
        FileError,
        ConversionError,
        ValidationError,
        RequiredError,
        RequiresError,
        ExcludesError,
        ExtrasError,
        ConfigError,
        InvalidError,
        HorribleError,
        OptionNotFound,
        ArgumentMismatch,
        BaseClass = 127
    };

    // Error definitions

    /// @defgroup error_group Errors
    /// @brief Errors thrown by CLI11
    ///
    /// These are the errors that can be thrown. Some of them, like CLI::Success, are not really errors.
    /// @{

    /// All errors derive from this one
    class Error : public std::runtime_error
    {
        int actual_exit_code;
        std::string error_name{ "Error" };

    public:
        int get_exit_code() const { return actual_exit_code; }

        std::string get_name() const { return error_name; }

        Error(std::string name, std::string msg, int exit_code = static_cast<int>(ExitCodes::BaseClass)) :
            runtime_error(msg),
            actual_exit_code(exit_code),
            error_name(std::move(name)) {}

        Error(std::string name, std::string msg, ExitCodes exit_code) :
            Error(name, msg, static_cast<int>(exit_code)) {}
    };

    // Note: Using Error::Error constructors does not work on GCC 4.7

    /// Construction errors (not in parsing)
    class ConstructionError : public Error
    {
        CLI11_ERROR_DEF(Error, ConstructionError)
    };

    /// Thrown when an option is set to conflicting values (non-vector and multi args, for example)
    class IncorrectConstruction : public ConstructionError
    {
        CLI11_ERROR_DEF(ConstructionError, IncorrectConstruction)
        CLI11_ERROR_SIMPLE(IncorrectConstruction)
        static IncorrectConstruction PositionalFlag(std::string name)
        {
            return IncorrectConstruction(name + ": Flags cannot be positional");
        }
        static IncorrectConstruction Set0Opt(std::string name)
        {
            return IncorrectConstruction(name + ": Cannot set 0 expected, use a flag instead");
        }
        static IncorrectConstruction SetFlag(std::string name)
        {
            return IncorrectConstruction(name + ": Cannot set an expected number for flags");
        }
        static IncorrectConstruction ChangeNotVector(std::string name)
        {
            return IncorrectConstruction(name + ": You can only change the expected arguments for vectors");
        }
        static IncorrectConstruction AfterMultiOpt(std::string name)
        {
            return IncorrectConstruction(
                name + ": You can't change expected arguments after you've changed the multi option policy!");
        }
        static IncorrectConstruction MissingOption(std::string name)
        {
            return IncorrectConstruction("Option " + name + " is not defined");
        }
        static IncorrectConstruction MultiOptionPolicy(std::string name)
        {
            return IncorrectConstruction(name + ": multi_option_policy only works for flags and exact value options");
        }
    };

    /// Thrown on construction of a bad name
    class BadNameString : public ConstructionError
    {
        CLI11_ERROR_DEF(ConstructionError, BadNameString)
        CLI11_ERROR_SIMPLE(BadNameString)
        static BadNameString OneCharName(std::string name) { return BadNameString("Invalid one char name: " + name); }
        static BadNameString BadLongName(std::string name) { return BadNameString("Bad long name: " + name); }
        static BadNameString DashesOnly(std::string name)
        {
            return BadNameString("Must have a name, not just dashes: " + name);
        }
        static BadNameString MultiPositionalNames(std::string name)
        {
            return BadNameString("Only one positional name allowed, remove: " + name);
        }
    };

    /// Thrown when an option already exists
    class OptionAlreadyAdded : public ConstructionError
    {
        CLI11_ERROR_DEF(ConstructionError, OptionAlreadyAdded)
        explicit OptionAlreadyAdded(std::string name) :
            OptionAlreadyAdded(name + " is already added", ExitCodes::OptionAlreadyAdded) {}
        static OptionAlreadyAdded Requires(std::string name, std::string other)
        {
            return OptionAlreadyAdded(name + " requires " + other, ExitCodes::OptionAlreadyAdded);
        }
        static OptionAlreadyAdded Excludes(std::string name, std::string other)
        {
            return OptionAlreadyAdded(name + " excludes " + other, ExitCodes::OptionAlreadyAdded);
        }
    };

    // Parsing errors

    /// Anything that can error in Parse
    class ParseError : public Error
    {
        CLI11_ERROR_DEF(Error, ParseError)
    };

    // Not really "errors"

    /// This is a successful completion on parsing, supposed to exit
    class Success : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, Success)
        Success() :
            Success("Successfully completed, should be caught and quit", ExitCodes::Success) {}
    };

    /// -h or --help on command line
    class CallForHelp : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, CallForHelp)
        CallForHelp() :
            CallForHelp("This should be caught in your main function, see examples", ExitCodes::Success) {}
    };

    /// Usually something like --help-all on command line
    class CallForAllHelp : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, CallForAllHelp)
        CallForAllHelp() :
            CallForAllHelp("This should be caught in your main function, see examples", ExitCodes::Success) {}
    };

    /// Does not output a diagnostic in CLI11_PARSE, but allows to return from main() with a specific error code.
    class RuntimeError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, RuntimeError)
        explicit RuntimeError(int exit_code = 1) :
            RuntimeError("Runtime error", exit_code) {}
    };

    /// Thrown when parsing an INI file and it is missing
    class FileError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, FileError)
        CLI11_ERROR_SIMPLE(FileError)
        static FileError Missing(std::string name) { return FileError(name + " was not readable (missing?)"); }
    };

    /// Thrown when conversion call back fails, such as when an int fails to coerce to a string
    class ConversionError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, ConversionError)
        CLI11_ERROR_SIMPLE(ConversionError)
        ConversionError(std::string member, std::string name) :
            ConversionError("The value " + member + " is not an allowed value for " + name) {}
        ConversionError(std::string name, std::vector<std::string> results) :
            ConversionError("Could not convert: " + name + " = " + detail::join(results)) {}
        static ConversionError TooManyInputsFlag(std::string name)
        {
            return ConversionError(name + ": too many inputs for a flag");
        }
        static ConversionError TrueFalse(std::string name)
        {
            return ConversionError(name + ": Should be true/false or a number");
        }
    };

    /// Thrown when validation of results fails
    class ValidationError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, ValidationError)
        CLI11_ERROR_SIMPLE(ValidationError)
        explicit ValidationError(std::string name, std::string msg) :
            ValidationError(name + ": " + msg) {}
    };

    /// Thrown when a required option is missing
    class RequiredError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, RequiredError)
        explicit RequiredError(std::string name) :
            RequiredError(name + " is required", ExitCodes::RequiredError) {}
        static RequiredError Subcommand(size_t min_subcom)
        {
            if (min_subcom == 1)
                return RequiredError("A subcommand");
            else
                return RequiredError("Requires at least " + std::to_string(min_subcom) + " subcommands",
                                     ExitCodes::RequiredError);
        }
        static RequiredError Option(size_t min_option, size_t max_option, size_t used, const std::string& option_list)
        {
            if ((min_option == 1) && (max_option == 1) && (used == 0))
                return RequiredError("Exactly 1 option from [" + option_list + "]");
            else if ((min_option == 1) && (max_option == 1) && (used > 1))
                return RequiredError("Exactly 1 option from [" + option_list + "] is required and " + std::to_string(used) +
                                         " were given",
                                     ExitCodes::RequiredError);
            else if ((min_option == 1) && (used == 0))
                return RequiredError("At least 1 option from [" + option_list + "]");
            else if (used < min_option)
                return RequiredError("Requires at least " + std::to_string(min_option) + " options used and only " +
                                         std::to_string(used) + "were given from [" + option_list + "]",
                                     ExitCodes::RequiredError);
            else if (max_option == 1)
                return RequiredError("Requires at most 1 options be given from [" + option_list + "]",
                                     ExitCodes::RequiredError);
            else
                return RequiredError("Requires at most " + std::to_string(max_option) + " options be used and " +
                                         std::to_string(used) + "were given from [" + option_list + "]",
                                     ExitCodes::RequiredError);
        }
    };

    /// Thrown when the wrong number of arguments has been received
    class ArgumentMismatch : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, ArgumentMismatch)
        CLI11_ERROR_SIMPLE(ArgumentMismatch)
        ArgumentMismatch(std::string name, int expected, size_t recieved) :
            ArgumentMismatch(expected > 0 ? ("Expected exactly " + std::to_string(expected) + " arguments to " + name +
                                             ", got " + std::to_string(recieved)) :
                                            ("Expected at least " + std::to_string(-expected) + " arguments to " + name +
                                             ", got " + std::to_string(recieved)),
                             ExitCodes::ArgumentMismatch) {}

        static ArgumentMismatch AtLeast(std::string name, int num)
        {
            return ArgumentMismatch(name + ": At least " + std::to_string(num) + " required");
        }
        static ArgumentMismatch TypedAtLeast(std::string name, int num, std::string type)
        {
            return ArgumentMismatch(name + ": " + std::to_string(num) + " required " + type + " missing");
        }
        static ArgumentMismatch FlagOverride(std::string name)
        {
            return ArgumentMismatch(name + " was given a disallowed flag override");
        }
    };

    /// Thrown when a requires option is missing
    class RequiresError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, RequiresError)
        RequiresError(std::string curname, std::string subname) :
            RequiresError(curname + " requires " + subname, ExitCodes::RequiresError) {}
    };

    /// Thrown when an excludes option is present
    class ExcludesError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, ExcludesError)
        ExcludesError(std::string curname, std::string subname) :
            ExcludesError(curname + " excludes " + subname, ExitCodes::ExcludesError) {}
    };

    /// Thrown when too many positionals or options are found
    class ExtrasError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, ExtrasError)
        explicit ExtrasError(std::vector<std::string> args) :
            ExtrasError((args.size() > 1 ? "The following arguments were not expected: " : "The following argument was not expected: ") +
                            detail::rjoin(args, " "),
                        ExitCodes::ExtrasError) {}
    };

    /// Thrown when extra values are found in an INI file
    class ConfigError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, ConfigError)
        CLI11_ERROR_SIMPLE(ConfigError)
        static ConfigError Extras(std::string item) { return ConfigError("INI was not able to parse " + item); }
        static ConfigError NotConfigurable(std::string item)
        {
            return ConfigError(item + ": This option is not allowed in a configuration file");
        }
    };

    /// Thrown when validation fails before parsing
    class InvalidError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, InvalidError)
        explicit InvalidError(std::string name) :
            InvalidError(name + ": Too many positional arguments with unlimited expected args", ExitCodes::InvalidError)
        {
        }
    };

    /// This is just a safety check to verify selection and parsing match - you should not ever see it
    /// Strings are directly added to this error, but again, it should never be seen.
    class HorribleError : public ParseError
    {
        CLI11_ERROR_DEF(ParseError, HorribleError)
        CLI11_ERROR_SIMPLE(HorribleError)
    };

    // After parsing

    /// Thrown when counting a non-existent option
    class OptionNotFound : public Error
    {
        CLI11_ERROR_DEF(Error, OptionNotFound)
        explicit OptionNotFound(std::string name) :
            OptionNotFound(name + " not found", ExitCodes::OptionNotFound) {}
    };

#undef CLI11_ERROR_DEF
#undef CLI11_ERROR_SIMPLE

    /// @}

} // namespace CLI

// From CLI/TypeTools.hpp:

namespace CLI
{
    // Type tools

    // Utilities for type enabling
    namespace detail
    {
        // Based generally on https://rmf.io/cxx11/almost-static-if
        /// Simple empty scoped class
        enum class enabler
        {
        };

        /// An instance to use in EnableIf
        constexpr enabler dummy = {};
    } // namespace detail

    /// A copy of enable_if_t from C++14, compatible with C++11.
    ///
    /// We could check to see if C++14 is being used, but it does not hurt to redefine this
    /// (even Google does this: https://github.com/google/skia/blob/master/include/private/SkTLogic.h)
    /// It is not in the std namespace anyway, so no harm done.
    template<bool B, class T = void>
    using enable_if_t = typename std::enable_if<B, T>::type;

    /// A copy of std::void_t from C++17 (helper for C++11 and C++14)
    template<typename... Ts>
    struct make_void
    {
        using type = void;
    };

    /// A copy of std::void_t from C++17 - same reasoning as enable_if_t, it does not hurt to redefine
    template<typename... Ts>
    using void_t = typename make_void<Ts...>::type;

    /// A copy of std::conditional_t from C++14 - same reasoning as enable_if_t, it does not hurt to redefine
    template<bool B, class T, class F>
    using conditional_t = typename std::conditional<B, T, F>::type;

    /// Check to see if something is a vector (fail check by default)
    template<typename T>
    struct is_vector : std::false_type
    {
    };

    /// Check to see if something is a vector (true if actually a vector)
    template<class T, class A>
    struct is_vector<std::vector<T, A>> : std::true_type
    {
    };

    /// Check to see if something is bool (fail check by default)
    template<typename T>
    struct is_bool : std::false_type
    {
    };

    /// Check to see if something is bool (true if actually a bool)
    template<>
    struct is_bool<bool> : std::true_type
    {
    };

    /// Check to see if something is a shared pointer
    template<typename T>
    struct is_shared_ptr : std::false_type
    {
    };

    /// Check to see if something is a shared pointer (True if really a shared pointer)
    template<typename T>
    struct is_shared_ptr<std::shared_ptr<T>> : std::true_type
    {
    };

    /// Check to see if something is a shared pointer (True if really a shared pointer)
    template<typename T>
    struct is_shared_ptr<const std::shared_ptr<T>> : std::true_type
    {
    };

    /// Check to see if something is copyable pointer
    template<typename T>
    struct is_copyable_ptr
    {
        static bool const value = is_shared_ptr<T>::value || std::is_pointer<T>::value;
    };

    /// This can be specialized to override the type deduction for IsMember.
    template<typename T>
    struct IsMemberType
    {
        using type = T;
    };

    /// The main custom type needed here is const char * should be a string.
    template<>
    struct IsMemberType<const char*>
    {
        using type = std::string;
    };

    namespace detail
    {
        // These are utilities for IsMember

        /// Handy helper to access the element_type generically. This is not part of is_copyable_ptr because it requires that
        /// pointer_traits<T> be valid.
        template<typename T>
        struct element_type
        {
            using type =
                typename std::conditional<is_copyable_ptr<T>::value, typename std::pointer_traits<T>::element_type, T>::type;
        };

        /// Combination of the element type and value type - remove pointer (including smart pointers) and get the value_type of
        /// the container
        template<typename T>
        struct element_value_type
        {
            using type = typename element_type<T>::type::value_type;
        };

        /// Adaptor for set-like structure: This just wraps a normal container in a few utilities that do almost nothing.
        template<typename T, typename _ = void>
        struct pair_adaptor : std::false_type
        {
            using value_type = typename T::value_type;
            using first_type = typename std::remove_const<value_type>::type;
            using second_type = typename std::remove_const<value_type>::type;

            /// Get the first value (really just the underlying value)
            template<typename Q>
            static auto first(Q&& pair_value) -> decltype(std::forward<Q>(pair_value))
            {
                return std::forward<Q>(pair_value);
            }
            /// Get the second value (really just the underlying value)
            template<typename Q>
            static auto second(Q&& pair_value) -> decltype(std::forward<Q>(pair_value))
            {
                return std::forward<Q>(pair_value);
            }
        };

        /// Adaptor for map-like structure (true version, must have key_type and mapped_type).
        /// This wraps a mapped container in a few utilities access it in a general way.
        template<typename T>
        struct pair_adaptor<
            T,
            conditional_t<false, void_t<typename T::value_type::first_type, typename T::value_type::second_type>, void>> : std::true_type
        {
            using value_type = typename T::value_type;
            using first_type = typename std::remove_const<typename value_type::first_type>::type;
            using second_type = typename std::remove_const<typename value_type::second_type>::type;

            /// Get the first value (really just the underlying value)
            template<typename Q>
            static auto first(Q&& pair_value) -> decltype(std::get<0>(std::forward<Q>(pair_value)))
            {
                return std::get<0>(std::forward<Q>(pair_value));
            }
            /// Get the second value (really just the underlying value)
            template<typename Q>
            static auto second(Q&& pair_value) -> decltype(std::get<1>(std::forward<Q>(pair_value)))
            {
                return std::get<1>(std::forward<Q>(pair_value));
            }
        };

        // Check for streamability
        // Based on https://stackoverflow.com/questions/22758291/how-can-i-detect-if-a-type-can-be-streamed-to-an-stdostream

        template<typename S, typename T>
        class is_streamable
        {
            template<typename SS, typename TT>
            static auto test(int) -> decltype(std::declval<SS&>() << std::declval<TT>(), std::true_type());

            template<typename, typename>
            static auto test(...) -> std::false_type;

        public:
            static const bool value = decltype(test<S, T>(0))::value;
        };

        /// Convert an object to a string (directly forward if this can become a string)
        template<typename T, enable_if_t<std::is_constructible<std::string, T>::value, detail::enabler> = detail::dummy>
        auto to_string(T&& value) -> decltype(std::forward<T>(value))
        {
            return std::forward<T>(value);
        }

        /// Convert an object to a string (streaming must be supported for that type)
        template<typename T,
                 enable_if_t<!std::is_constructible<std::string, T>::value && is_streamable<std::stringstream, T>::value,
                             detail::enabler> = detail::dummy>
        std::string to_string(T&& value)
        {
            std::stringstream stream;
            stream << value;
            return stream.str();
        }

        /// If conversion is not supported, return an empty string (streaming is not supported for that type)
        template<typename T,
                 enable_if_t<!std::is_constructible<std::string, T>::value && !is_streamable<std::stringstream, T>::value,
                             detail::enabler> = detail::dummy>
        std::string to_string(T&&)
        {
            return std::string{};
        }

        // Type name print

        /// Was going to be based on
        ///  http://stackoverflow.com/questions/1055452/c-get-name-of-type-in-template
        /// But this is cleaner and works better in this case

        template<typename T,
                 enable_if_t<std::is_integral<T>::value && std::is_signed<T>::value, detail::enabler> = detail::dummy>
        constexpr const char* type_name()
        {
            return "INT";
        }

        template<typename T,
                 enable_if_t<std::is_integral<T>::value && std::is_unsigned<T>::value, detail::enabler> = detail::dummy>
        constexpr const char* type_name()
        {
            return "UINT";
        }

        template<typename T, enable_if_t<std::is_floating_point<T>::value, detail::enabler> = detail::dummy>
        constexpr const char* type_name()
        {
            return "FLOAT";
        }

        /// This one should not be used, since vector types print the internal type
        template<typename T, enable_if_t<is_vector<T>::value, detail::enabler> = detail::dummy>
        constexpr const char* type_name()
        {
            return "VECTOR";
        }
        /// Print name for enumeration types
        template<typename T, enable_if_t<std::is_enum<T>::value, detail::enabler> = detail::dummy>
        constexpr const char* type_name()
        {
            return "ENUM";
        }

        /// Print for all other types
        template<typename T,
                 enable_if_t<!std::is_floating_point<T>::value && !std::is_integral<T>::value && !is_vector<T>::value &&
                                 !std::is_enum<T>::value,
                             detail::enabler> = detail::dummy>
        constexpr const char* type_name()
        {
            return "TEXT";
        }

        // Lexical cast

        /// Convert a flag into an integer value  typically binary flags
        inline int64_t to_flag_value(std::string val)
        {
            static const std::string trueString("true");
            static const std::string falseString("false");
            if (val == trueString)
            {
                return 1;
            }
            if (val == falseString)
            {
                return -1;
            }
            val = detail::to_lower(val);
            int64_t ret;
            if (val.size() == 1)
            {
                switch (val[0])
                {
                case '0':
                case 'f':
                case 'n':
                case '-':
                    ret = -1;
                    break;
                case '1':
                case 't':
                case 'y':
                case '+':
                    ret = 1;
                    break;
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                case '8':
                case '9':
                    ret = val[0] - '0';
                    break;
                default:
                    throw std::invalid_argument("unrecognized character");
                }
                return ret;
            }
            if (val == trueString || val == "on" || val == "yes" || val == "enable")
            {
                ret = 1;
            }
            else if (val == falseString || val == "off" || val == "no" || val == "disable")
            {
                ret = -1;
            }
            else
            {
                ret = std::stoll(val);
            }
            return ret;
        }

        /// Signed integers
        template<
            typename T,
            enable_if_t<std::is_integral<T>::value && std::is_signed<T>::value && !is_bool<T>::value && !std::is_enum<T>::value,
                        detail::enabler> = detail::dummy>
        bool lexical_cast(std::string input, T& output)
        {
            try
            {
                size_t n = 0;
                long long output_ll = std::stoll(input, &n, 0);
                output = static_cast<T>(output_ll);
                return n == input.size() && static_cast<long long>(output) == output_ll;
            }
            catch (const std::invalid_argument&)
            {
                return false;
            }
            catch (const std::out_of_range&)
            {
                return false;
            }
        }

        /// Unsigned integers
        template<typename T,
                 enable_if_t<std::is_integral<T>::value && std::is_unsigned<T>::value && !is_bool<T>::value, detail::enabler> =
                     detail::dummy>
        bool lexical_cast(std::string input, T& output)
        {
            if (!input.empty() && input.front() == '-')
                return false; // std::stoull happily converts negative values to junk without any errors.

            try
            {
                size_t n = 0;
                unsigned long long output_ll = std::stoull(input, &n, 0);
                output = static_cast<T>(output_ll);
                return n == input.size() && static_cast<unsigned long long>(output) == output_ll;
            }
            catch (const std::invalid_argument&)
            {
                return false;
            }
            catch (const std::out_of_range&)
            {
                return false;
            }
        }

        /// Boolean values
        template<typename T, enable_if_t<is_bool<T>::value, detail::enabler> = detail::dummy>
        bool lexical_cast(std::string input, T& output)
        {
            try
            {
                auto out = to_flag_value(input);
                output = (out > 0);
                return true;
            }
            catch (const std::invalid_argument&)
            {
                return false;
            }
        }

        /// Floats
        template<typename T, enable_if_t<std::is_floating_point<T>::value, detail::enabler> = detail::dummy>
        bool lexical_cast(std::string input, T& output)
        {
            try
            {
                size_t n = 0;
                output = static_cast<T>(std::stold(input, &n));
                return n == input.size();
            }
            catch (const std::invalid_argument&)
            {
                return false;
            }
            catch (const std::out_of_range&)
            {
                return false;
            }
        }

        /// String and similar
        template<typename T,
                 enable_if_t<!std::is_floating_point<T>::value && !std::is_integral<T>::value &&
                                 std::is_assignable<T&, std::string>::value,
                             detail::enabler> = detail::dummy>
        bool lexical_cast(std::string input, T& output)
        {
            output = input;
            return true;
        }

        /// Enumerations
        template<typename T, enable_if_t<std::is_enum<T>::value, detail::enabler> = detail::dummy>
        bool lexical_cast(std::string input, T& output)
        {
            typename std::underlying_type<T>::type val;
            bool retval = detail::lexical_cast(input, val);
            if (!retval)
            {
                return false;
            }
            output = static_cast<T>(val);
            return true;
        }

        /// Non-string parsable
        template<typename T,
                 enable_if_t<!std::is_floating_point<T>::value && !std::is_integral<T>::value &&
                                 !std::is_assignable<T&, std::string>::value && !std::is_enum<T>::value,
                             detail::enabler> = detail::dummy>
        bool lexical_cast(std::string input, T& output)
        {
            std::istringstream is;

            is.str(input);
            is >> output;
            return !is.fail() && !is.rdbuf()->in_avail();
        }

        /// Sum a vector of flag representations
        /// The flag vector produces a series of strings in a vector,  simple true is represented by a "1",  simple false is by
        /// "-1" an if numbers are passed by some fashion they are captured as well so the function just checks for the most
        /// common true and false strings then uses stoll to convert the rest for summing
        template<typename T,
                 enable_if_t<std::is_integral<T>::value && std::is_unsigned<T>::value, detail::enabler> = detail::dummy>
        void sum_flag_vector(const std::vector<std::string>& flags, T& output)
        {
            int64_t count{ 0 };
            for (auto& flag : flags)
            {
                count += detail::to_flag_value(flag);
            }
            output = (count > 0) ? static_cast<T>(count) : T{ 0 };
        }

        /// Sum a vector of flag representations
        /// The flag vector produces a series of strings in a vector,  simple true is represented by a "1",  simple false is by
        /// "-1" an if numbers are passed by some fashion they are captured as well so the function just checks for the most
        /// common true and false strings then uses stoll to convert the rest for summing
        template<typename T,
                 enable_if_t<std::is_integral<T>::value && std::is_signed<T>::value, detail::enabler> = detail::dummy>
        void sum_flag_vector(const std::vector<std::string>& flags, T& output)
        {
            int64_t count{ 0 };
            for (auto& flag : flags)
            {
                count += detail::to_flag_value(flag);
            }
            output = static_cast<T>(count);
        }

    } // namespace detail
} // namespace CLI

// From CLI/Split.hpp:

namespace CLI
{
    namespace detail
    {
        // Returns false if not a short option. Otherwise, sets opt name and rest and returns true
        inline bool split_short(const std::string& current, std::string& name, std::string& rest)
        {
            if (current.size() > 1 && current[0] == '-' && valid_first_char(current[1]))
            {
                name = current.substr(1, 1);
                rest = current.substr(2);
                return true;
            }
            else
                return false;
        }

        // Returns false if not a long option. Otherwise, sets opt name and other side of = and returns true
        inline bool split_long(const std::string& current, std::string& name, std::string& value)
        {
            if (current.size() > 2 && current.substr(0, 2) == "--" && valid_first_char(current[2]))
            {
                auto loc = current.find_first_of('=');
                if (loc != std::string::npos)
                {
                    name = current.substr(2, loc - 2);
                    value = current.substr(loc + 1);
                }
                else
                {
                    name = current.substr(2);
                    value = "";
                }
                return true;
            }
            else
                return false;
        }

        // Returns false if not a windows style option. Otherwise, sets opt name and value and returns true
        inline bool split_windows_style(const std::string& current, std::string& name, std::string& value)
        {
            if (current.size() > 1 && current[0] == '/' && valid_first_char(current[1]))
            {
                auto loc = current.find_first_of(':');
                if (loc != std::string::npos)
                {
                    name = current.substr(1, loc - 1);
                    value = current.substr(loc + 1);
                }
                else
                {
                    name = current.substr(1);
                    value = "";
                }
                return true;
            }
            else
                return false;
        }

        // Splits a string into multiple long and short names
        inline std::vector<std::string> split_names(std::string current)
        {
            std::vector<std::string> output;
            size_t val;
            while ((val = current.find(",")) != std::string::npos)
            {
                output.push_back(trim_copy(current.substr(0, val)));
                current = current.substr(val + 1);
            }
            output.push_back(trim_copy(current));
            return output;
        }

        /// extract default flag values either {def} or starting with a !
        inline std::vector<std::pair<std::string, std::string>> get_default_flag_values(const std::string& str)
        {
            std::vector<std::string> flags = split_names(str);
            flags.erase(std::remove_if(flags.begin(),
                                       flags.end(),
                                       [](const std::string& name) {
                                           return ((name.empty()) || (!(((name.find_first_of('{') != std::string::npos) &&
                                                                         (name.back() == '}')) ||
                                                                        (name[0] == '!'))));
                                       }),
                        flags.end());
            std::vector<std::pair<std::string, std::string>> output;
            output.reserve(flags.size());
            for (auto& flag : flags)
            {
                auto def_start = flag.find_first_of('{');
                std::string defval = "false";
                if ((def_start != std::string::npos) && (flag.back() == '}'))
                {
                    defval = flag.substr(def_start + 1);
                    defval.pop_back();
                    flag.erase(def_start, std::string::npos);
                }
                flag.erase(0, flag.find_first_not_of("-!"));
                output.emplace_back(flag, defval);
            }
            return output;
        }

        /// Get a vector of short names, one of long names, and a single name
        inline std::tuple<std::vector<std::string>, std::vector<std::string>, std::string>
        get_names(const std::vector<std::string>& input)
        {
            std::vector<std::string> short_names;
            std::vector<std::string> long_names;
            std::string pos_name;

            for (std::string name : input)
            {
                if (name.length() == 0)
                    continue;
                else if (name.length() > 1 && name[0] == '-' && name[1] != '-')
                {
                    if (name.length() == 2 && valid_first_char(name[1]))
                        short_names.emplace_back(1, name[1]);
                    else
                        throw BadNameString::OneCharName(name);
                }
                else if (name.length() > 2 && name.substr(0, 2) == "--")
                {
                    name = name.substr(2);
                    if (valid_name_string(name))
                        long_names.push_back(name);
                    else
                        throw BadNameString::BadLongName(name);
                }
                else if (name == "-" || name == "--")
                {
                    throw BadNameString::DashesOnly(name);
                }
                else
                {
                    if (pos_name.length() > 0)
                        throw BadNameString::MultiPositionalNames(name);
                    pos_name = name;
                }
            }

            return std::tuple<std::vector<std::string>, std::vector<std::string>, std::string>(
                short_names, long_names, pos_name);
        }

    } // namespace detail
} // namespace CLI

// From CLI/ConfigFwd.hpp:

namespace CLI
{
    class App;

    namespace detail
    {
        /// Comma separated join, adds quotes if needed
        inline std::string ini_join(std::vector<std::string> args)
        {
            std::ostringstream s;
            size_t start = 0;
            for (const auto& arg : args)
            {
                if (start++ > 0)
                    s << " ";

                auto it = std::find_if(arg.begin(), arg.end(), [](char ch) { return std::isspace<char>(ch, std::locale()); });
                if (it == arg.end())
                    s << arg;
                else if (arg.find_first_of('\"') == std::string::npos)
                    s << '\"' << arg << '\"';
                else
                    s << '\'' << arg << '\'';
            }

            return s.str();
        }

    } // namespace detail

    /// Holds values to load into Options
    struct ConfigItem
    {
        /// This is the list of parents
        std::vector<std::string> parents;

        /// This is the name
        std::string name;

        /// Listing of inputs
        std::vector<std::string> inputs;

        /// The list of parents and name joined by "."
        std::string fullname() const
        {
            std::vector<std::string> tmp = parents;
            tmp.emplace_back(name);
            return detail::join(tmp, ".");
        }
    };

    /// This class provides a converter for configuration files.
    class Config
    {
    protected:
        std::vector<ConfigItem> items;

    public:
        /// Convert an app into a configuration
        virtual std::string to_config(const App*, bool, bool, std::string) const = 0;

        /// Convert a configuration into an app
        virtual std::vector<ConfigItem> from_config(std::istream&) const = 0;

        /// Get a flag value
        virtual std::string to_flag(const ConfigItem& item) const
        {
            if (item.inputs.size() == 1)
            {
                return item.inputs.at(0);
            }
            throw ConversionError::TooManyInputsFlag(item.fullname());
        }

        /// Parse a config file, throw an error (ParseError:ConfigParseError or FileError) on failure
        std::vector<ConfigItem> from_file(const std::string& name)
        {
            std::ifstream input{ name };
            if (!input.good())
                throw FileError::Missing(name);

            return from_config(input);
        }

        /// Virtual destructor
        virtual ~Config() = default;
    };

    /// This converter works with INI files
    class ConfigINI : public Config
    {
    public:
        std::string to_config(const App*, bool default_also, bool write_description, std::string prefix) const override;

        std::vector<ConfigItem> from_config(std::istream& input) const override
        {
            std::string line;
            std::string section = "default";

            std::vector<ConfigItem> output;

            while (getline(input, line))
            {
                std::vector<std::string> items_buffer;

                detail::trim(line);
                size_t len = line.length();
                if (len > 1 && line[0] == '[' && line[len - 1] == ']')
                {
                    section = line.substr(1, len - 2);
                }
                else if (len > 0 && line[0] != ';')
                {
                    output.emplace_back();
                    ConfigItem& out = output.back();

                    // Find = in string, split and recombine
                    auto pos = line.find('=');
                    if (pos != std::string::npos)
                    {
                        out.name = detail::trim_copy(line.substr(0, pos));
                        std::string item = detail::trim_copy(line.substr(pos + 1));
                        items_buffer = detail::split_up(item);
                    }
                    else
                    {
                        out.name = detail::trim_copy(line);
                        items_buffer = { "ON" };
                    }

                    if (detail::to_lower(section) != "default")
                    {
                        out.parents = { section };
                    }

                    if (out.name.find('.') != std::string::npos)
                    {
                        std::vector<std::string> plist = detail::split(out.name, '.');
                        out.name = plist.back();
                        plist.pop_back();
                        out.parents.insert(out.parents.end(), plist.begin(), plist.end());
                    }

                    out.inputs.insert(std::end(out.inputs), std::begin(items_buffer), std::end(items_buffer));
                }
            }
            return output;
        }
    };

} // namespace CLI

// From CLI/Validators.hpp:

namespace CLI
{
    class Option;

    /// @defgroup validator_group Validators

    /// @brief Some validators that are provided
    ///
    /// These are simple `std::string(const std::string&)` validators that are useful. They return
    /// a string if the validation fails. A custom struct is provided, as well, with the same user
    /// semantics, but with the ability to provide a new type name.
    /// @{

    ///
    class Validator
    {
    protected:
        /// This is the description function, if empty the description_ will be used
        std::function<std::string()> desc_function_{ []() { return std::string{}; } };

        /// This it the base function that is to be called.
        /// Returns a string error message if validation fails.
        std::function<std::string(std::string&)> func_{ [](std::string&) { return std::string{}; } };
        /// The name for search purposes of the Validator
        std::string name_;
        /// Enable for Validator to allow it to be disabled if need be
        bool active_{ true };
        /// specify that a validator should not modify the input
        bool non_modifying_{ false };

    public:
        Validator() = default;
        /// Construct a Validator with just the description string
        explicit Validator(std::string validator_desc) :
            desc_function_([validator_desc]() { return validator_desc; }) {}
        // Construct Validator from basic information
        Validator(std::function<std::string(std::string&)> op, std::string validator_desc, std::string validator_name = "") :
            desc_function_([validator_desc]() { return validator_desc; }),
            func_(std::move(op)),
            name_(std::move(validator_name)) {}
        /// Set the Validator operation function
        Validator& operation(std::function<std::string(std::string&)> op)
        {
            func_ = std::move(op);
            return *this;
        }
        /// This is the required operator for a Validator - provided to help
        /// users (CLI11 uses the member `func` directly)
        std::string operator()(std::string& str) const
        {
            std::string retstring;
            if (active_)
            {
                if (non_modifying_)
                {
                    std::string value = str;
                    retstring = func_(value);
                }
                else
                {
                    retstring = func_(str);
                }
            }
            return retstring;
        };

        /// This is the required operator for a Validator - provided to help
        /// users (CLI11 uses the member `func` directly)
        std::string operator()(const std::string& str) const
        {
            std::string value = str;
            return (active_) ? func_(value) : std::string{};
        };

        /// Specify the type string
        Validator& description(std::string validator_desc)
        {
            desc_function_ = [validator_desc]() { return validator_desc; };
            return *this;
        }
        /// Generate type description information for the Validator
        std::string get_description() const
        {
            if (active_)
            {
                return desc_function_();
            }
            return std::string{};
        }
        /// Specify the type string
        Validator& name(std::string validator_name)
        {
            name_ = std::move(validator_name);
            return *this;
        }
        /// Get the name of the Validator
        const std::string& get_name() const { return name_; }
        /// Specify whether the Validator is active or not
        Validator& active(bool active_val = true)
        {
            active_ = active_val;
            return *this;
        }

        /// Specify whether the Validator can be modifying or not
        Validator& non_modifying(bool no_modify = true)
        {
            non_modifying_ = no_modify;
            return *this;
        }

        /// Get a boolean if the validator is active
        bool get_active() const { return active_; }

        /// Get a boolean if the validator is allowed to modify the input returns true if it can modify the input
        bool get_modifying() const { return !non_modifying_; }

        /// Combining validators is a new validator. Type comes from left validator if function, otherwise only set if the
        /// same.
        Validator operator&(const Validator& other) const
        {
            Validator newval;

            newval._merge_description(*this, other, " AND ");

            // Give references (will make a copy in lambda function)
            const std::function<std::string(std::string & filename)>& f1 = func_;
            const std::function<std::string(std::string & filename)>& f2 = other.func_;

            newval.func_ = [f1, f2](std::string& input) {
                std::string s1 = f1(input);
                std::string s2 = f2(input);
                if (!s1.empty() && !s2.empty())
                    return std::string("(") + s1 + ") AND (" + s2 + ")";
                else
                    return s1 + s2;
            };

            newval.active_ = (active_ & other.active_);
            return newval;
        }

        /// Combining validators is a new validator. Type comes from left validator if function, otherwise only set if the
        /// same.
        Validator operator|(const Validator& other) const
        {
            Validator newval;

            newval._merge_description(*this, other, " OR ");

            // Give references (will make a copy in lambda function)
            const std::function<std::string(std::string&)>& f1 = func_;
            const std::function<std::string(std::string&)>& f2 = other.func_;

            newval.func_ = [f1, f2](std::string& input) {
                std::string s1 = f1(input);
                std::string s2 = f2(input);
                if (s1.empty() || s2.empty())
                    return std::string();
                else
                    return std::string("(") + s1 + ") OR (" + s2 + ")";
            };
            newval.active_ = (active_ & other.active_);
            return newval;
        }

        /// Create a validator that fails when a given validator succeeds
        Validator operator!() const
        {
            Validator newval;
            const std::function<std::string()>& dfunc1 = desc_function_;
            newval.desc_function_ = [dfunc1]() {
                auto str = dfunc1();
                return (!str.empty()) ? std::string("NOT ") + str : std::string{};
            };
            // Give references (will make a copy in lambda function)
            const std::function<std::string(std::string & res)>& f1 = func_;

            newval.func_ = [f1, dfunc1](std::string& test) -> std::string {
                std::string s1 = f1(test);
                if (s1.empty())
                {
                    return std::string("check ") + dfunc1() + " succeeded improperly";
                }
                else
                    return std::string{};
            };
            newval.active_ = active_;
            return newval;
        }

    private:
        void _merge_description(const Validator& val1, const Validator& val2, const std::string& merger)
        {
            const std::function<std::string()>& dfunc1 = val1.desc_function_;
            const std::function<std::string()>& dfunc2 = val2.desc_function_;

            desc_function_ = [=]() {
                std::string f1 = dfunc1();
                std::string f2 = dfunc2();
                if ((f1.empty()) || (f2.empty()))
                {
                    return f1 + f2;
                }
                return std::string("(") + f1 + ")" + merger + "(" + f2 + ")";
            };
        }
    };

    /// Class wrapping some of the accessors of Validator
    class CustomValidator : public Validator
    {
    public:
    };
    // The implementation of the built in validators is using the Validator class;
    // the user is only expected to use the const (static) versions (since there's no setup).
    // Therefore, this is in detail.
    namespace detail
    {
        /// Check for an existing file (returns error message if check fails)
        class ExistingFileValidator : public Validator
        {
        public:
            ExistingFileValidator() :
                Validator("FILE")
            {
                func_ = [](std::string& filename) {
                    struct stat buffer;
                    bool exist = stat(filename.c_str(), &buffer) == 0;
                    bool is_dir = (buffer.st_mode & S_IFDIR) != 0;
                    if (!exist)
                    {
                        return "File does not exist: " + filename;
                    }
                    else if (is_dir)
                    {
                        return "File is actually a directory: " + filename;
                    }
                    return std::string();
                };
            }
        };

        /// Check for an existing directory (returns error message if check fails)
        class ExistingDirectoryValidator : public Validator
        {
        public:
            ExistingDirectoryValidator() :
                Validator("DIR")
            {
                func_ = [](std::string& filename) {
                    struct stat buffer;
                    bool exist = stat(filename.c_str(), &buffer) == 0;
                    bool is_dir = (buffer.st_mode & S_IFDIR) != 0;
                    if (!exist)
                    {
                        return "Directory does not exist: " + filename;
                    }
                    else if (!is_dir)
                    {
                        return "Directory is actually a file: " + filename;
                    }
                    return std::string();
                };
            }
        };

        /// Check for an existing path
        class ExistingPathValidator : public Validator
        {
        public:
            ExistingPathValidator() :
                Validator("PATH(existing)")
            {
                func_ = [](std::string& filename) {
                    struct stat buffer;
                    bool const exist = stat(filename.c_str(), &buffer) == 0;
                    if (!exist)
                    {
                        return "Path does not exist: " + filename;
                    }
                    return std::string();
                };
            }
        };

        /// Check for an non-existing path
        class NonexistentPathValidator : public Validator
        {
        public:
            NonexistentPathValidator() :
                Validator("PATH(non-existing)")
            {
                func_ = [](std::string& filename) {
                    struct stat buffer;
                    bool exist = stat(filename.c_str(), &buffer) == 0;
                    if (exist)
                    {
                        return "Path already exists: " + filename;
                    }
                    return std::string();
                };
            }
        };

        /// Validate the given string is a legal ipv4 address
        class IPV4Validator : public Validator
        {
        public:
            IPV4Validator() :
                Validator("IPV4")
            {
                func_ = [](std::string& ip_addr) {
                    auto result = CLI::detail::split(ip_addr, '.');
                    if (result.size() != 4)
                    {
                        return "Invalid IPV4 address must have four parts " + ip_addr;
                    }
                    int num;
                    bool retval = true;
                    for (const auto& var : result)
                    {
                        retval &= detail::lexical_cast(var, num);
                        if (!retval)
                        {
                            return "Failed parsing number " + var;
                        }
                        if (num < 0 || num > 255)
                        {
                            return "Each IP number must be between 0 and 255 " + var;
                        }
                    }
                    return std::string();
                };
            }
        };

        /// Validate the argument is a number and greater than or equal to 0
        class PositiveNumber : public Validator
        {
        public:
            PositiveNumber() :
                Validator("POSITIVE")
            {
                func_ = [](std::string& number_str) {
                    int number;
                    if (!detail::lexical_cast(number_str, number))
                    {
                        return "Failed parsing number " + number_str;
                    }
                    if (number < 0)
                    {
                        return "Number less then 0 " + number_str;
                    }
                    return std::string();
                };
            }
        };

        /// Validate the argument is a number and greater than or equal to 0
        class Number : public Validator
        {
        public:
            Number() :
                Validator("NUMBER")
            {
                func_ = [](std::string& number_str) {
                    double number;
                    if (!detail::lexical_cast(number_str, number))
                    {
                        return "Failed parsing as a number " + number_str;
                    }
                    return std::string();
                };
            }
        };

    } // namespace detail

    // Static is not needed here, because global const implies static.

    /// Check for existing file (returns error message if check fails)
    const detail::ExistingFileValidator ExistingFile;

    /// Check for an existing directory (returns error message if check fails)
    const detail::ExistingDirectoryValidator ExistingDirectory;

    /// Check for an existing path
    const detail::ExistingPathValidator ExistingPath;

    /// Check for an non-existing path
    const detail::NonexistentPathValidator NonexistentPath;

    /// Check for an IP4 address
    const detail::IPV4Validator ValidIPV4;

    /// Check for a positive number
    const detail::PositiveNumber PositiveNumber;

    /// Check for a number
    const detail::Number Number;

    /// Produce a range (factory). Min and max are inclusive.
    class Range : public Validator
    {
    public:
        /// This produces a range with min and max inclusive.
        ///
        /// Note that the constructor is templated, but the struct is not, so C++17 is not
        /// needed to provide nice syntax for Range(a,b).
        template<typename T>
        Range(T min, T max)
        {
            std::stringstream out;
            out << detail::type_name<T>() << " in [" << min << " - " << max << "]";
            description(out.str());

            func_ = [min, max](std::string& input) {
                T val;
                bool converted = detail::lexical_cast(input, val);
                if ((!converted) || (val < min || val > max))
                    return "Value " + input + " not in range " + std::to_string(min) + " to " + std::to_string(max);

                return std::string();
            };
        }

        /// Range of one value is 0 to value
        template<typename T>
        explicit Range(T max) :
            Range(static_cast<T>(0), max)
        {
        }
    };

    /// Produce a bounded range (factory). Min and max are inclusive.
    class Bound : public Validator
    {
    public:
        /// This bounds a value with min and max inclusive.
        ///
        /// Note that the constructor is templated, but the struct is not, so C++17 is not
        /// needed to provide nice syntax for Range(a,b).
        template<typename T>
        Bound(T min, T max)
        {
            std::stringstream out;
            out << detail::type_name<T>() << " bounded to [" << min << " - " << max << "]";
            description(out.str());

            func_ = [min, max](std::string& input) {
                T val;
                bool converted = detail::lexical_cast(input, val);
                if (!converted)
                {
                    return "Value " + input + " could not be converted";
                }
                if (val < min)
                    input = detail::as_string(min);
                else if (val > max)
                    input = detail::as_string(max);

                return std::string();
            };
        }

        /// Range of one value is 0 to value
        template<typename T>
        explicit Bound(T max) :
            Bound(static_cast<T>(0), max)
        {
        }
    };

    namespace detail
    {
        template<typename T,
                 enable_if_t<is_copyable_ptr<typename std::remove_reference<T>::type>::value, detail::enabler> = detail::dummy>
        auto smart_deref(T value) -> decltype(*value)
        {
            return *value;
        }

        template<
            typename T,
            enable_if_t<!is_copyable_ptr<typename std::remove_reference<T>::type>::value, detail::enabler> = detail::dummy>
        typename std::remove_reference<T>::type& smart_deref(T& value)
        {
            return value;
        }
        /// Generate a string representation of a set
        template<typename T>
        std::string generate_set(const T& set)
        {
            using element_t = typename detail::element_type<T>::type;
            using iteration_type_t = typename detail::pair_adaptor<element_t>::value_type; // the type of the object pair
            std::string out(1, '{');
            out.append(detail::join(
                detail::smart_deref(set),
                [](const iteration_type_t& v) { return detail::pair_adaptor<element_t>::first(v); },
                ","));
            out.push_back('}');
            return out;
        }

        /// Generate a string representation of a map
        template<typename T>
        std::string generate_map(const T& map, bool key_only = false)
        {
            using element_t = typename detail::element_type<T>::type;
            using iteration_type_t = typename detail::pair_adaptor<element_t>::value_type; // the type of the object pair
            std::string out(1, '{');
            out.append(detail::join(
                detail::smart_deref(map),
                [key_only](const iteration_type_t& v) {
                    auto res = detail::as_string(detail::pair_adaptor<element_t>::first(v));
                    if (!key_only)
                    {
                        res += "->" + detail::as_string(detail::pair_adaptor<element_t>::second(v));
                    }
                    return res;
                },
                ","));
            out.push_back('}');
            return out;
        }

        template<typename>
        struct sfinae_true : std::true_type
        {
        };
        /// Function to check for the existence of a member find function which presumably is more efficient than looping over
        /// everything
        template<typename T, typename V>
        static auto test_find(int) -> sfinae_true<decltype(std::declval<T>().find(std::declval<V>()))>;
        template<typename, typename V>
        static auto test_find(long) -> std::false_type;

        template<typename T, typename V>
        struct has_find : decltype(test_find<T, V>(0))
        {
        };

        /// A search function
        template<typename T, typename V, enable_if_t<!has_find<T, V>::value, detail::enabler> = detail::dummy>
        auto search(const T& set, const V& val) -> std::pair<bool, decltype(std::begin(detail::smart_deref(set)))>
        {
            using element_t = typename detail::element_type<T>::type;
            auto& setref = detail::smart_deref(set);
            auto it = std::find_if(std::begin(setref), std::end(setref), [&val](decltype(*std::begin(setref)) v) {
                return (detail::pair_adaptor<element_t>::first(v) == val);
            });
            return { (it != std::end(setref)), it };
        }

        /// A search function that uses the built in find function
        template<typename T, typename V, enable_if_t<has_find<T, V>::value, detail::enabler> = detail::dummy>
        auto search(const T& set, const V& val) -> std::pair<bool, decltype(std::begin(detail::smart_deref(set)))>
        {
            auto& setref = detail::smart_deref(set);
            auto it = setref.find(val);
            return { (it != std::end(setref)), it };
        }

        /// A search function with a filter function
        template<typename T, typename V>
        auto search(const T& set, const V& val, const std::function<V(V)>& filter_function)
            -> std::pair<bool, decltype(std::begin(detail::smart_deref(set)))>
        {
            using element_t = typename detail::element_type<T>::type;
            // do the potentially faster first search
            auto res = search(set, val);
            if ((res.first) || (!(filter_function)))
            {
                return res;
            }
            // if we haven't found it do the longer linear search with all the element translations
            auto& setref = detail::smart_deref(set);
            auto it = std::find_if(std::begin(setref), std::end(setref), [&](decltype(*std::begin(setref)) v) {
                V a = detail::pair_adaptor<element_t>::first(v);
                a = filter_function(a);
                return (a == val);
            });
            return { (it != std::end(setref)), it };
        }

        /// Performs a *= b; if it doesn't cause integer overflow. Returns false otherwise.
        template<typename T>
        typename std::enable_if<std::is_integral<T>::value, bool>::type checked_multiply(T& a, T b)
        {
            if (a == 0 || b == 0)
            {
                a *= b;
                return true;
            }
            T c = a * b;
            if (c / a != b)
            {
                return false;
            }
            a = c;
            return true;
        }

        /// Performs a *= b; if it doesn't equal infinity. Returns false otherwise.
        template<typename T>
        typename std::enable_if<std::is_floating_point<T>::value, bool>::type checked_multiply(T& a, T b)
        {
            T c = a * b;
            if (std::isinf(c) && !std::isinf(a) && !std::isinf(b))
            {
                return false;
            }
            a = c;
            return true;
        }

    } // namespace detail
    /// Verify items are in a set
    class IsMember : public Validator
    {
    public:
        using filter_fn_t = std::function<std::string(std::string)>;

        /// This allows in-place construction using an initializer list
        template<typename T, typename... Args>
        explicit IsMember(std::initializer_list<T> values, Args&&... args) :
            IsMember(std::vector<T>(values), std::forward<Args>(args)...)
        {
        }

        /// This checks to see if an item is in a set (empty function)
        template<typename T>
        explicit IsMember(T&& set) :
            IsMember(std::forward<T>(set), nullptr)
        {
        }

        /// This checks to see if an item is in a set: pointer or copy version. You can pass in a function that will filter
        /// both sides of the comparison before computing the comparison.
        template<typename T, typename F>
        explicit IsMember(T set, F filter_function)
        {
            // Get the type of the contained item - requires a container have ::value_type
            // if the type does not have first_type and second_type, these are both value_type
            using element_t = typename detail::element_type<T>::type; // Removes (smart) pointers if needed
            using item_t = typename detail::pair_adaptor<element_t>::first_type; // Is value_type if not a map

            using local_item_t = typename IsMemberType<item_t>::type; // This will convert bad types to good ones
                // (const char * to std::string)

            // Make a local copy of the filter function, using a std::function if not one already
            std::function<local_item_t(local_item_t)> filter_fn = filter_function;

            // This is the type name for help, it will take the current version of the set contents
            desc_function_ = [set]() { return detail::generate_set(detail::smart_deref(set)); };

            // This is the function that validates
            // It stores a copy of the set pointer-like, so shared_ptr will stay alive
            func_ = [set, filter_fn](std::string& input) {
                local_item_t b;
                if (!detail::lexical_cast(input, b))
                {
                    throw ValidationError(input); // name is added later
                }
                if (filter_fn)
                {
                    b = filter_fn(b);
                }
                auto res = detail::search(set, b, filter_fn);
                if (res.first)
                {
                    // Make sure the version in the input string is identical to the one in the set
                    if (filter_fn)
                    {
                        input = detail::as_string(detail::pair_adaptor<element_t>::first(*(res.second)));
                    }

                    // Return empty error string (success)
                    return std::string{};
                }

                // If you reach this point, the result was not found
                std::string out(" not in ");
                out += detail::generate_set(detail::smart_deref(set));
                return out;
            };
        }

        /// You can pass in as many filter functions as you like, they nest (string only currently)
        template<typename T, typename... Args>
        IsMember(T&& set, filter_fn_t filter_fn_1, filter_fn_t filter_fn_2, Args&&... other) :
            IsMember(
                std::forward<T>(set),
                [filter_fn_1, filter_fn_2](std::string a) { return filter_fn_2(filter_fn_1(a)); },
                other...)
        {
        }
    };

    /// definition of the default transformation object
    template<typename T>
    using TransformPairs = std::vector<std::pair<std::string, T>>;

    /// Translate named items to other or a value set
    class Transformer : public Validator
    {
    public:
        using filter_fn_t = std::function<std::string(std::string)>;

        /// This allows in-place construction
        template<typename... Args>
        explicit Transformer(std::initializer_list<std::pair<std::string, std::string>> values, Args&&... args) :
            Transformer(TransformPairs<std::string>(values), std::forward<Args>(args)...)
        {
        }

        /// direct map of std::string to std::string
        template<typename T>
        explicit Transformer(T&& mapping) :
            Transformer(std::forward<T>(mapping), nullptr)
        {
        }

        /// This checks to see if an item is in a set: pointer or copy version. You can pass in a function that will filter
        /// both sides of the comparison before computing the comparison.
        template<typename T, typename F>
        explicit Transformer(T mapping, F filter_function)
        {
            static_assert(detail::pair_adaptor<typename detail::element_type<T>::type>::value,
                          "mapping must produce value pairs");
            // Get the type of the contained item - requires a container have ::value_type
            // if the type does not have first_type and second_type, these are both value_type
            using element_t = typename detail::element_type<T>::type; // Removes (smart) pointers if needed
            using item_t = typename detail::pair_adaptor<element_t>::first_type; // Is value_type if not a map
            using local_item_t = typename IsMemberType<item_t>::type; // This will convert bad types to good ones
                // (const char * to std::string)

            // Make a local copy of the filter function, using a std::function if not one already
            std::function<local_item_t(local_item_t)> filter_fn = filter_function;

            // This is the type name for help, it will take the current version of the set contents
            desc_function_ = [mapping]() { return detail::generate_map(detail::smart_deref(mapping)); };

            func_ = [mapping, filter_fn](std::string& input) {
                local_item_t b;
                if (!detail::lexical_cast(input, b))
                {
                    return std::string();
                    // there is no possible way we can match anything in the mapping if we can't convert so just return
                }
                if (filter_fn)
                {
                    b = filter_fn(b);
                }
                auto res = detail::search(mapping, b, filter_fn);
                if (res.first)
                {
                    input = detail::as_string(detail::pair_adaptor<element_t>::second(*res.second));
                }
                return std::string{};
            };
        }

        /// You can pass in as many filter functions as you like, they nest
        template<typename T, typename... Args>
        Transformer(T&& mapping, filter_fn_t filter_fn_1, filter_fn_t filter_fn_2, Args&&... other) :
            Transformer(
                std::forward<T>(mapping),
                [filter_fn_1, filter_fn_2](std::string a) { return filter_fn_2(filter_fn_1(a)); },
                other...)
        {
        }
    };

    /// translate named items to other or a value set
    class CheckedTransformer : public Validator
    {
    public:
        using filter_fn_t = std::function<std::string(std::string)>;

        /// This allows in-place construction
        template<typename... Args>
        explicit CheckedTransformer(std::initializer_list<std::pair<std::string, std::string>> values, Args&&... args) :
            CheckedTransformer(TransformPairs<std::string>(values), std::forward<Args>(args)...)
        {
        }

        /// direct map of std::string to std::string
        template<typename T>
        explicit CheckedTransformer(T mapping) :
            CheckedTransformer(std::move(mapping), nullptr)
        {
        }

        /// This checks to see if an item is in a set: pointer or copy version. You can pass in a function that will filter
        /// both sides of the comparison before computing the comparison.
        template<typename T, typename F>
        explicit CheckedTransformer(T mapping, F filter_function)
        {
            static_assert(detail::pair_adaptor<typename detail::element_type<T>::type>::value,
                          "mapping must produce value pairs");
            // Get the type of the contained item - requires a container have ::value_type
            // if the type does not have first_type and second_type, these are both value_type
            using element_t = typename detail::element_type<T>::type; // Removes (smart) pointers if needed
            using item_t = typename detail::pair_adaptor<element_t>::first_type; // Is value_type if not a map
            using local_item_t = typename IsMemberType<item_t>::type; // This will convert bad types to good ones
                // (const char * to std::string)
            using iteration_type_t = typename detail::pair_adaptor<element_t>::value_type; // the type of the object pair //
                // the type of the object pair

            // Make a local copy of the filter function, using a std::function if not one already
            std::function<local_item_t(local_item_t)> filter_fn = filter_function;

            auto tfunc = [mapping]() {
                std::string out("value in ");
                out += detail::generate_map(detail::smart_deref(mapping)) + " OR {";
                out += detail::join(
                    detail::smart_deref(mapping),
                    [](const iteration_type_t& v) { return detail::as_string(detail::pair_adaptor<element_t>::second(v)); },
                    ",");
                out.push_back('}');
                return out;
            };

            desc_function_ = tfunc;

            func_ = [mapping, tfunc, filter_fn](std::string& input) {
                local_item_t b;
                bool converted = detail::lexical_cast(input, b);
                if (converted)
                {
                    if (filter_fn)
                    {
                        b = filter_fn(b);
                    }
                    auto res = detail::search(mapping, b, filter_fn);
                    if (res.first)
                    {
                        input = detail::as_string(detail::pair_adaptor<element_t>::second(*res.second));
                        return std::string{};
                    }
                }
                for (const auto& v : detail::smart_deref(mapping))
                {
                    auto output_string = detail::as_string(detail::pair_adaptor<element_t>::second(v));
                    if (output_string == input)
                    {
                        return std::string();
                    }
                }

                return "Check " + input + " " + tfunc() + " FAILED";
            };
        }

        /// You can pass in as many filter functions as you like, they nest
        template<typename T, typename... Args>
        CheckedTransformer(T&& mapping, filter_fn_t filter_fn_1, filter_fn_t filter_fn_2, Args&&... other) :
            CheckedTransformer(
                std::forward<T>(mapping),
                [filter_fn_1, filter_fn_2](std::string a) { return filter_fn_2(filter_fn_1(a)); },
                other...)
        {
        }
    };

    /// Helper function to allow ignore_case to be passed to IsMember or Transform
    inline std::string ignore_case(std::string item) { return detail::to_lower(item); }

    /// Helper function to allow ignore_underscore to be passed to IsMember or Transform
    inline std::string ignore_underscore(std::string item) { return detail::remove_underscore(item); }

    /// Helper function to allow checks to ignore spaces to be passed to IsMember or Transform
    inline std::string ignore_space(std::string item)
    {
        item.erase(std::remove(std::begin(item), std::end(item), ' '), std::end(item));
        item.erase(std::remove(std::begin(item), std::end(item), '\t'), std::end(item));
        return item;
    }

    /// Multiply a number by a factor using given mapping.
    /// Can be used to write transforms for SIZE or DURATION inputs.
    ///
    /// Example:
    ///   With mapping = `{"b"->1, "kb"->1024, "mb"->1024*1024}`
    ///   one can recognize inputs like "100", "12kb", "100 MB",
    ///   that will be automatically transformed to 100, 14448, 104857600.
    ///
    /// Output number type matches the type in the provided mapping.
    /// Therefore, if it is required to interpret real inputs like "0.42 s",
    /// the mapping should be of a type <string, float> or <string, double>.
    class AsNumberWithUnit : public Validator
    {
    public:
        /// Adjust AsNumberWithUnit behavior.
        /// CASE_SENSITIVE/CASE_INSENSITIVE controls how units are matched.
        /// UNIT_OPTIONAL/UNIT_REQUIRED throws ValidationError
        ///   if UNIT_REQUIRED is set and unit literal is not found.
        enum Options
        {
            CASE_SENSITIVE = 0,
            CASE_INSENSITIVE = 1,
            UNIT_OPTIONAL = 0,
            UNIT_REQUIRED = 2,
            DEFAULT = CASE_INSENSITIVE | UNIT_OPTIONAL
        };

        template<typename Number>
        explicit AsNumberWithUnit(std::map<std::string, Number> mapping,
                                  Options opts = DEFAULT,
                                  const std::string& unit_name = "UNIT")
        {
            description(generate_description<Number>(unit_name, opts));
            validate_mapping(mapping, opts);

            // transform function
            func_ = [mapping, opts](std::string& input) -> std::string {
                Number num;

                detail::rtrim(input);
                if (input.empty())
                {
                    throw ValidationError("Input is empty");
                }

                // Find split position between number and prefix
                auto unit_begin = input.end();
                while (unit_begin > input.begin() && std::isalpha(*(unit_begin - 1), std::locale()))
                {
                    --unit_begin;
                }

                std::string unit{ unit_begin, input.end() };
                input.resize(static_cast<size_t>(std::distance(input.begin(), unit_begin)));
                detail::trim(input);

                if (opts & UNIT_REQUIRED && unit.empty())
                {
                    throw ValidationError("Missing mandatory unit");
                }
                if (opts & CASE_INSENSITIVE)
                {
                    unit = detail::to_lower(unit);
                }

                bool converted = detail::lexical_cast(input, num);
                if (!converted)
                {
                    throw ValidationError("Value " + input + " could not be converted to " + detail::type_name<Number>());
                }

                if (unit.empty())
                {
                    // No need to modify input if no unit passed
                    return {};
                }

                // find corresponding factor
                auto it = mapping.find(unit);
                if (it == mapping.end())
                {
                    throw ValidationError(unit +
                                          " unit not recognized. "
                                          "Allowed values: " +
                                          detail::generate_map(mapping, true));
                }

                // perform safe multiplication
                bool ok = detail::checked_multiply(num, it->second);
                if (!ok)
                {
                    throw ValidationError(detail::as_string(num) + " multiplied by " + unit +
                                          " factor would cause number overflow. Use smaller value.");
                }
                input = detail::as_string(num);

                return {};
            };
        }

    private:
        /// Check that mapping contains valid units.
        /// Update mapping for CASE_INSENSITIVE mode.
        template<typename Number>
        static void validate_mapping(std::map<std::string, Number>& mapping, Options opts)
        {
            for (auto& kv : mapping)
            {
                if (kv.first.empty())
                {
                    throw ValidationError("Unit must not be empty.");
                }
                if (!detail::isalpha(kv.first))
                {
                    throw ValidationError("Unit must contain only letters.");
                }
            }

            // make all units lowercase if CASE_INSENSITIVE
            if (opts & CASE_INSENSITIVE)
            {
                std::map<std::string, Number> lower_mapping;
                for (auto& kv : mapping)
                {
                    auto s = detail::to_lower(kv.first);
                    if (lower_mapping.count(s))
                    {
                        throw ValidationError("Several matching lowercase unit representations are found: " + s);
                    }
                    lower_mapping[detail::to_lower(kv.first)] = kv.second;
                }
                mapping = std::move(lower_mapping);
            }
        }

        /// Generate description like this: NUMBER [UNIT]
        template<typename Number>
        static std::string generate_description(const std::string& name, Options opts)
        {
            std::stringstream out;
            out << detail::type_name<Number>() << ' ';
            if (opts & UNIT_REQUIRED)
            {
                out << name;
            }
            else
            {
                out << '[' << name << ']';
            }
            return out.str();
        }
    };

    /// Converts a human-readable size string (with unit literal) to uin64_t size.
    /// Example:
    ///   "100" => 100
    ///   "1 b" => 100
    ///   "10Kb" => 10240 // you can configure this to be interpreted as kilobyte (*1000) or kibibyte (*1024)
    ///   "10 KB" => 10240
    ///   "10 kb" => 10240
    ///   "10 kib" => 10240 // *i, *ib are always interpreted as *bibyte (*1024)
    ///   "10kb" => 10240
    ///   "2 MB" => 2097152
    ///   "2 EiB" => 2^61 // Units up to exibyte are supported
    class AsSizeValue : public AsNumberWithUnit
    {
    public:
        using result_t = uint64_t;

        /// If kb_is_1000 is true,
        /// interpret 'kb', 'k' as 1000 and 'kib', 'ki' as 1024
        /// (same applies to higher order units as well).
        /// Otherwise, interpret all literals as factors of 1024.
        /// The first option is formally correct, but
        /// the second interpretation is more wide-spread
        /// (see https://en.wikipedia.org/wiki/Binary_prefix).
        explicit AsSizeValue(bool kb_is_1000) :
            AsNumberWithUnit(get_mapping(kb_is_1000))
        {
            if (kb_is_1000)
            {
                description("SIZE [b, kb(=1000b), kib(=1024b), ...]");
            }
            else
            {
                description("SIZE [b, kb(=1024b), ...]");
            }
        }

    private:
        /// Get <size unit, factor> mapping
        static std::map<std::string, result_t> init_mapping(bool kb_is_1000)
        {
            std::map<std::string, result_t> m;
            result_t k_factor = kb_is_1000 ? 1000 : 1024;
            result_t ki_factor = 1024;
            result_t k = 1;
            result_t ki = 1;
            m["b"] = 1;
            for (std::string p : { "k", "m", "g", "t", "p", "e" })
            {
                k *= k_factor;
                ki *= ki_factor;
                m[p] = k;
                m[p + "b"] = k;
                m[p + "i"] = ki;
                m[p + "ib"] = ki;
            }
            return m;
        }

        /// Cache calculated mapping
        static std::map<std::string, result_t> get_mapping(bool kb_is_1000)
        {
            if (kb_is_1000)
            {
                static auto m = init_mapping(true);
                return m;
            }
            else
            {
                static auto m = init_mapping(false);
                return m;
            }
        }
    };

    namespace detail
    {
        /// Split a string into a program name and command line arguments
        /// the string is assumed to contain a file name followed by other arguments
        /// the return value contains is a pair with the first argument containing the program name and the second
        /// everything else.
        inline std::pair<std::string, std::string> split_program_name(std::string commandline)
        {
            // try to determine the programName
            std::pair<std::string, std::string> vals;
            trim(commandline);
            auto esp = commandline.find_first_of(' ', 1);
            while (!ExistingFile(commandline.substr(0, esp)).empty())
            {
                esp = commandline.find_first_of(' ', esp + 1);
                if (esp == std::string::npos)
                {
                    // if we have reached the end and haven't found a valid file just assume the first argument is the
                    // program name
                    esp = commandline.find_first_of(' ', 1);
                    break;
                }
            }
            vals.first = commandline.substr(0, esp);
            rtrim(vals.first);
            // strip the program name
            vals.second = (esp != std::string::npos) ? commandline.substr(esp + 1) : std::string{};
            ltrim(vals.second);
            return vals;
        }

    } // namespace detail
    /// @}

} // namespace CLI

// From CLI/FormatterFwd.hpp:

namespace CLI
{
    class Option;
    class App;

    /// This enum signifies the type of help requested
    ///
    /// This is passed in by App; all user classes must accept this as
    /// the second argument.

    enum class AppFormatMode
    {
        Normal, //< The normal, detailed help
        All, //< A fully expanded help
        Sub, //< Used when printed as part of expanded subcommand
    };

    /// This is the minimum requirements to run a formatter.
    ///
    /// A user can subclass this is if they do not care at all
    /// about the structure in CLI::Formatter.
    class FormatterBase
    {
    protected:
        /// @name Options
        ///@{

        /// The width of the first column
        size_t column_width_{ 30 };

        /// @brief The required help printout labels (user changeable)
        /// Values are Needs, Excludes, etc.
        std::map<std::string, std::string> labels_;

        ///@}
        /// @name Basic
        ///@{

    public:
        FormatterBase() = default;
        FormatterBase(const FormatterBase&) = default;
        FormatterBase(FormatterBase&&) = default;

        /// Adding a destructor in this form to work around bug in GCC 4.7
        virtual ~FormatterBase() noexcept {} // NOLINT(modernize-use-equals-default)

        /// This is the key method that puts together help
        virtual std::string make_help(const App*, std::string, AppFormatMode) const = 0;

        ///@}
        /// @name Setters
        ///@{

        /// Set the "REQUIRED" label
        void label(std::string key, std::string val) { labels_[key] = val; }

        /// Set the column width
        void column_width(size_t val) { column_width_ = val; }

        ///@}
        /// @name Getters
        ///@{

        /// Get the current value of a name (REQUIRED, etc.)
        std::string get_label(std::string key) const
        {
            if (labels_.find(key) == labels_.end())
                return key;
            else
                return labels_.at(key);
        }

        /// Get the current column width
        size_t get_column_width() const { return column_width_; }

        ///@}
    };

    /// This is a specialty override for lambda functions
    class FormatterLambda final : public FormatterBase
    {
        using funct_t = std::function<std::string(const App*, std::string, AppFormatMode)>;

        /// The lambda to hold and run
        funct_t lambda_;

    public:
        /// Create a FormatterLambda with a lambda function
        explicit FormatterLambda(funct_t funct) :
            lambda_(std::move(funct)) {}

        /// Adding a destructor (mostly to make GCC 4.7 happy)
        ~FormatterLambda() noexcept override {} // NOLINT(modernize-use-equals-default)

        /// This will simply call the lambda function
        std::string make_help(const App* app, std::string name, AppFormatMode mode) const override
        {
            return lambda_(app, name, mode);
        }
    };

    /// This is the default Formatter for CLI11. It pretty prints help output, and is broken into quite a few
    /// overridable methods, to be highly customizable with minimal effort.
    class Formatter : public FormatterBase
    {
    public:
        Formatter() = default;
        Formatter(const Formatter&) = default;
        Formatter(Formatter&&) = default;

        /// @name Overridables
        ///@{

        /// This prints out a group of options with title
        ///
        virtual std::string make_group(std::string group, bool is_positional, std::vector<const Option*> opts) const;

        /// This prints out just the positionals "group"
        virtual std::string make_positionals(const App* app) const;

        /// This prints out all the groups of options
        std::string make_groups(const App* app, AppFormatMode mode) const;

        /// This prints out all the subcommands
        virtual std::string make_subcommands(const App* app, AppFormatMode mode) const;

        /// This prints out a subcommand
        virtual std::string make_subcommand(const App* sub) const;

        /// This prints out a subcommand in help-all
        virtual std::string make_expanded(const App* sub) const;

        /// This prints out all the groups of options
        virtual std::string make_footer(const App* app) const;

        /// This displays the description line
        virtual std::string make_description(const App* app) const;

        /// This displays the usage line
        virtual std::string make_usage(const App* app, std::string name) const;

        /// This puts everything together
        std::string make_help(const App*, std::string, AppFormatMode) const override;

        ///@}
        /// @name Options
        ///@{

        /// This prints out an option help line, either positional or optional form
        virtual std::string make_option(const Option* opt, bool is_positional) const
        {
            std::stringstream out;
            detail::format_help(
                out, make_option_name(opt, is_positional) + make_option_opts(opt), make_option_desc(opt), column_width_);
            return out.str();
        }

        /// @brief This is the name part of an option, Default: left column
        virtual std::string make_option_name(const Option*, bool) const;

        /// @brief This is the options part of the name, Default: combined into left column
        virtual std::string make_option_opts(const Option*) const;

        /// @brief This is the description. Default: Right column, on new line if left column too large
        virtual std::string make_option_desc(const Option*) const;

        /// @brief This is used to print the name on the USAGE line
        virtual std::string make_option_usage(const Option* opt) const;

        ///@}
    };

} // namespace CLI

// From CLI/Option.hpp:

namespace CLI
{
    using results_t = std::vector<std::string>;
    using callback_t = std::function<bool(results_t)>;

    class Option;
    class App;

    using Option_p = std::unique_ptr<Option>;

    enum class MultiOptionPolicy : char
    {
        Throw,
        TakeLast,
        TakeFirst,
        Join
    };

    /// This is the CRTP base class for Option and OptionDefaults. It was designed this way
    /// to share parts of the class; an OptionDefaults can copy to an Option.
    template<typename CRTP>
    class OptionBase
    {
        friend App;

    protected:
        /// The group membership
        std::string group_ = std::string("Options");

        /// True if this is a required option
        bool required_{ false };

        /// Ignore the case when matching (option, not value)
        bool ignore_case_{ false };

        /// Ignore underscores when matching (option, not value)
        bool ignore_underscore_{ false };

        /// Allow this option to be given in a configuration file
        bool configurable_{ true };

        /// Disable overriding flag values with '=value'
        bool disable_flag_override_{ false };

        /// Specify a delimiter character for vector arguments
        char delimiter_{ '\0' };

        /// Automatically capture default value
        bool always_capture_default_{ false };

        /// Policy for multiple arguments when `expected_ == 1`  (can be set on bool flags, too)
        MultiOptionPolicy multi_option_policy_{ MultiOptionPolicy::Throw };

        /// Copy the contents to another similar class (one based on OptionBase)
        template<typename T>
        void copy_to(T* other) const
        {
            other->group(group_);
            other->required(required_);
            other->ignore_case(ignore_case_);
            other->ignore_underscore(ignore_underscore_);
            other->configurable(configurable_);
            other->disable_flag_override(disable_flag_override_);
            other->delimiter(delimiter_);
            other->always_capture_default(always_capture_default_);
            other->multi_option_policy(multi_option_policy_);
        }

    public:
        // setters

        /// Changes the group membership
        CRTP* group(std::string name)
        {
            group_ = name;
            return static_cast<CRTP*>(this);
        }

        /// Set the option as required
        CRTP* required(bool value = true)
        {
            required_ = value;
            return static_cast<CRTP*>(this);
        }

        /// Support Plumbum term
        CRTP* mandatory(bool value = true) { return required(value); }

        CRTP* always_capture_default(bool value = true)
        {
            always_capture_default_ = value;
            return static_cast<CRTP*>(this);
        }

        // Getters

        /// Get the group of this option
        const std::string& get_group() const { return group_; }

        /// True if this is a required option
        bool get_required() const { return required_; }

        /// The status of ignore case
        bool get_ignore_case() const { return ignore_case_; }

        /// The status of ignore_underscore
        bool get_ignore_underscore() const { return ignore_underscore_; }

        /// The status of configurable
        bool get_configurable() const { return configurable_; }

        /// The status of configurable
        bool get_disable_flag_override() const { return disable_flag_override_; }

        /// Get the current delimeter char
        char get_delimiter() const { return delimiter_; }

        /// Return true if this will automatically capture the default value for help printing
        bool get_always_capture_default() const { return always_capture_default_; }

        /// The status of the multi option policy
        MultiOptionPolicy get_multi_option_policy() const { return multi_option_policy_; }

        // Shortcuts for multi option policy

        /// Set the multi option policy to take last
        CRTP* take_last()
        {
            auto self = static_cast<CRTP*>(this);
            self->multi_option_policy(MultiOptionPolicy::TakeLast);
            return self;
        }

        /// Set the multi option policy to take last
        CRTP* take_first()
        {
            auto self = static_cast<CRTP*>(this);
            self->multi_option_policy(MultiOptionPolicy::TakeFirst);
            return self;
        }

        /// Set the multi option policy to take last
        CRTP* join()
        {
            auto self = static_cast<CRTP*>(this);
            self->multi_option_policy(MultiOptionPolicy::Join);
            return self;
        }

        /// Allow in a configuration file
        CRTP* configurable(bool value = true)
        {
            configurable_ = value;
            return static_cast<CRTP*>(this);
        }

        /// Allow in a configuration file
        CRTP* delimiter(char value = '\0')
        {
            delimiter_ = value;
            return static_cast<CRTP*>(this);
        }
    };

    /// This is a version of OptionBase that only supports setting values,
    /// for defaults. It is stored as the default option in an App.
    class OptionDefaults : public OptionBase<OptionDefaults>
    {
    public:
        OptionDefaults() = default;

        // Methods here need a different implementation if they are Option vs. OptionDefault

        /// Take the last argument if given multiple times
        OptionDefaults* multi_option_policy(MultiOptionPolicy value = MultiOptionPolicy::Throw)
        {
            multi_option_policy_ = value;
            return this;
        }

        /// Ignore the case of the option name
        OptionDefaults* ignore_case(bool value = true)
        {
            ignore_case_ = value;
            return this;
        }

        /// Ignore underscores in the option name
        OptionDefaults* ignore_underscore(bool value = true)
        {
            ignore_underscore_ = value;
            return this;
        }

        /// Disable overriding flag values with an '=<value>' segment
        OptionDefaults* disable_flag_override(bool value = true)
        {
            disable_flag_override_ = value;
            return this;
        }

        /// set a delimiter character to split up single arguments to treat as multiple inputs
        OptionDefaults* delimiter(char value = '\0')
        {
            delimiter_ = value;
            return this;
        }
    };

    class Option : public OptionBase<Option>
    {
        friend App;

    protected:
        /// @name Names
        ///@{

        /// A list of the short names (`-a`) without the leading dashes
        std::vector<std::string> snames_;

        /// A list of the long names (`--a`) without the leading dashes
        std::vector<std::string> lnames_;

        /// A list of the flag names with the appropriate default value, the first part of the pair should be duplicates of
        /// what is in snames or lnames but will trigger a particular response on a flag
        std::vector<std::pair<std::string, std::string>> default_flag_values_;

        /// a list of flag names with specified default values;
        std::vector<std::string> fnames_;

        /// A positional name
        std::string pname_;

        /// If given, check the environment for this option
        std::string envname_;

        ///@}
        /// @name Help
        ///@{

        /// The description for help strings
        std::string description_;

        /// A human readable default value, either manually set, captured, or captured by default
        std::string default_str_;

        /// A human readable type value, set when App creates this
        ///
        /// This is a lambda function so "types" can be dynamic, such as when a set prints its contents.
        std::function<std::string()> type_name_{ []() { return std::string(); } };

        /// Run this function to capture a default (ignore if empty)
        std::function<std::string()> default_function_;

        ///@}
        /// @name Configuration
        ///@{

        /// The number of arguments that make up one option. -1=unlimited (vector-like), 0=flag, 1=normal option,
        /// 2=complex/pair, etc. Set only when the option is created; this is intrinsic to the type. Eventually, -2 may mean
        /// vector of pairs.
        int type_size_{ 1 };

        /// The number of expected values, type_size_ must be < 0. Ignored for flag. N < 0 means at least -N values.
        int expected_{ 1 };

        /// A list of validators to run on each value parsed
        std::vector<Validator> validators_;

        /// A list of options that are required with this option
        std::set<Option*> needs_;

        /// A list of options that are excluded with this option
        std::set<Option*> excludes_;

        ///@}
        /// @name Other
        ///@{

        /// Remember the parent app
        App* parent_;

        /// Options store a callback to do all the work
        callback_t callback_;

        ///@}
        /// @name Parsing results
        ///@{

        /// Results of parsing
        results_t results_;

        /// Whether the callback has run (needed for INI parsing)
        bool callback_run_{ false };

        ///@}

        /// Making an option by hand is not defined, it must be made by the App class
        Option(std::string option_name,
               std::string option_description,
               std::function<bool(results_t)> callback,
               App* parent) :
            description_(std::move(option_description)),
            parent_(parent),
            callback_(std::move(callback))
        {
            std::tie(snames_, lnames_, pname_) = detail::get_names(detail::split_names(option_name));
        }

    public:
        /// @name Basic
        ///@{

        /// Count the total number of times an option was passed
        size_t count() const { return results_.size(); }

        /// True if the option was not passed
        size_t empty() const { return results_.empty(); }

        /// This class is true if option is passed.
        operator bool() const { return !empty(); }

        /// Clear the parsed results (mostly for testing)
        void clear() { results_.clear(); }

        ///@}
        /// @name Setting options
        ///@{

        /// Set the number of expected arguments (Flags don't use this)
        Option* expected(int value)
        {
            // Break if this is a flag
            if (type_size_ == 0)
                throw IncorrectConstruction::SetFlag(get_name(true, true));

            // Setting 0 is not allowed
            else if (value == 0)
                throw IncorrectConstruction::Set0Opt(get_name());

            // No change is okay, quit now
            else if (expected_ == value)
                return this;

            // Type must be a vector
            else if (type_size_ >= 0)
                throw IncorrectConstruction::ChangeNotVector(get_name());

            // TODO: Can support multioption for non-1 values (except for join)
            else if (value != 1 && multi_option_policy_ != MultiOptionPolicy::Throw)
                throw IncorrectConstruction::AfterMultiOpt(get_name());

            expected_ = value;
            return this;
        }

        /// Adds a Validator with a built in type name
        Option* check(Validator validator, std::string validator_name = "")
        {
            validator.non_modifying();
            validators_.push_back(std::move(validator));
            if (!validator_name.empty())
                validators_.front().name(validator_name);
            return this;
        }

        /// Adds a Validator. Takes a const string& and returns an error message (empty if conversion/check is okay).
        Option* check(std::function<std::string(const std::string&)> validator,
                      std::string validator_description = "",
                      std::string validator_name = "")
        {
            validators_.emplace_back(validator, std::move(validator_description), std::move(validator_name));
            validators_.back().non_modifying();
            return this;
        }

        /// Adds a transforming validator with a built in type name
        Option* transform(Validator validator, std::string validator_name = "")
        {
            validators_.insert(validators_.begin(), std::move(validator));
            if (!validator_name.empty())
                validators_.front().name(validator_name);
            return this;
        }

        /// Adds a validator-like function that can change result
        Option* transform(std::function<std::string(std::string)> func,
                          std::string transform_description = "",
                          std::string transform_name = "")
        {
            validators_.insert(validators_.begin(),
                               Validator(
                                   [func](std::string& val) {
                                       val = func(val);
                                       return std::string{};
                                   },
                                   std::move(transform_description),
                                   std::move(transform_name)));

            return this;
        }

        /// Adds a user supplied function to run on each item passed in (communicate though lambda capture)
        Option* each(std::function<void(std::string)> func)
        {
            validators_.emplace_back(
                [func](std::string& inout) {
                    func(inout);
                    return std::string{};
                },
                std::string{});
            return this;
        }
        /// Get a named Validator
        Validator* get_validator(const std::string& validator_name = "")
        {
            for (auto& validator : validators_)
            {
                if (validator_name == validator.get_name())
                {
                    return &validator;
                }
            }
            if ((validator_name.empty()) && (!validators_.empty()))
            {
                return &(validators_.front());
            }
            throw OptionNotFound(std::string("Validator ") + validator_name + " Not Found");
        }
        /// Sets required options
        Option* needs(Option* opt)
        {
            auto tup = needs_.insert(opt);
            if (!tup.second)
                throw OptionAlreadyAdded::Requires(get_name(), opt->get_name());
            return this;
        }

        /// Can find a string if needed
        template<typename T = App>
        Option* needs(std::string opt_name)
        {
            for (const Option_p& opt : dynamic_cast<T*>(parent_)->options_)
                if (opt.get() != this && opt->check_name(opt_name))
                    return needs(opt.get());
            throw IncorrectConstruction::MissingOption(opt_name);
        }

        /// Any number supported, any mix of string and Opt
        template<typename A, typename B, typename... ARG>
        Option* needs(A opt, B opt1, ARG... args)
        {
            needs(opt);
            return needs(opt1, args...);
        }

        /// Remove needs link from an option. Returns true if the option really was in the needs list.
        bool remove_needs(Option* opt)
        {
            auto iterator = std::find(std::begin(needs_), std::end(needs_), opt);

            if (iterator != std::end(needs_))
            {
                needs_.erase(iterator);
                return true;
            }
            else
            {
                return false;
            }
        }

        /// Sets excluded options
        Option* excludes(Option* opt)
        {
            excludes_.insert(opt);

            // Help text should be symmetric - excluding a should exclude b
            opt->excludes_.insert(this);

            // Ignoring the insert return value, excluding twice is now allowed.
            // (Mostly to allow both directions to be excluded by user, even though the library does it for you.)

            return this;
        }

        /// Can find a string if needed
        template<typename T = App>
        Option* excludes(std::string opt_name)
        {
            for (const Option_p& opt : dynamic_cast<T*>(parent_)->options_)
                if (opt.get() != this && opt->check_name(opt_name))
                    return excludes(opt.get());
            throw IncorrectConstruction::MissingOption(opt_name);
        }

        /// Any number supported, any mix of string and Opt
        template<typename A, typename B, typename... ARG>
        Option* excludes(A opt, B opt1, ARG... args)
        {
            excludes(opt);
            return excludes(opt1, args...);
        }

        /// Remove needs link from an option. Returns true if the option really was in the needs list.
        bool remove_excludes(Option* opt)
        {
            auto iterator = std::find(std::begin(excludes_), std::end(excludes_), opt);

            if (iterator != std::end(excludes_))
            {
                excludes_.erase(iterator);
                return true;
            }
            else
            {
                return false;
            }
        }

        /// Sets environment variable to read if no option given
        Option* envname(std::string name)
        {
            envname_ = name;
            return this;
        }

        /// Ignore case
        ///
        /// The template hides the fact that we don't have the definition of App yet.
        /// You are never expected to add an argument to the template here.
        template<typename T = App>
        Option* ignore_case(bool value = true)
        {
            ignore_case_ = value;
            auto* parent = dynamic_cast<T*>(parent_);

            for (const Option_p& opt : parent->options_)
                if (opt.get() != this && *opt == *this)
                    throw OptionAlreadyAdded(opt->get_name(true, true));

            return this;
        }

        /// Ignore underscores in the option names
        ///
        /// The template hides the fact that we don't have the definition of App yet.
        /// You are never expected to add an argument to the template here.
        template<typename T = App>
        Option* ignore_underscore(bool value = true)
        {
            ignore_underscore_ = value;
            auto* parent = dynamic_cast<T*>(parent_);
            for (const Option_p& opt : parent->options_)
                if (opt.get() != this && *opt == *this)
                    throw OptionAlreadyAdded(opt->get_name(true, true));

            return this;
        }

        /// Take the last argument if given multiple times (or another policy)
        Option* multi_option_policy(MultiOptionPolicy value = MultiOptionPolicy::Throw)
        {
            if (get_items_expected() < 0)
                throw IncorrectConstruction::MultiOptionPolicy(get_name());
            multi_option_policy_ = value;
            return this;
        }

        /// disable flag overrides
        Option* disable_flag_override(bool value = true)
        {
            disable_flag_override_ = value;
            return this;
        }
        ///@}
        /// @name Accessors
        ///@{

        /// The number of arguments the option expects
        int get_type_size() const { return type_size_; }

        /// The environment variable associated to this value
        std::string get_envname() const { return envname_; }

        /// The set of options needed
        std::set<Option*> get_needs() const { return needs_; }

        /// The set of options excluded
        std::set<Option*> get_excludes() const { return excludes_; }

        /// The default value (for help printing) DEPRECATED Use get_default_str() instead
        CLI11_DEPRECATED("Use get_default_str() instead")
        std::string get_defaultval() const { return default_str_; }

        /// The default value (for help printing)
        std::string get_default_str() const { return default_str_; }

        /// Get the callback function
        callback_t get_callback() const { return callback_; }

        /// Get the long names
        const std::vector<std::string> get_lnames() const { return lnames_; }

        /// Get the short names
        const std::vector<std::string> get_snames() const { return snames_; }

        /// get the flag names with specified default values
        const std::vector<std::string> get_fnames() const { return fnames_; }

        /// The number of times the option expects to be included
        int get_expected() const { return expected_; }

        /// \brief The total number of expected values (including the type)
        /// This is positive if exactly this number is expected, and negative for at least N values
        ///
        /// v = fabs(size_type*expected)
        /// !MultiOptionPolicy::Throw
        ///           | Expected < 0  | Expected == 0 | Expected > 0
        /// Size < 0  |      -v       |       0       |     -v
        /// Size == 0 |       0       |       0       |      0
        /// Size > 0  |      -v       |       0       |     -v       // Expected must be 1
        ///
        /// MultiOptionPolicy::Throw
        ///           | Expected < 0  | Expected == 0 | Expected > 0
        /// Size < 0  |      -v       |       0       |      v
        /// Size == 0 |       0       |       0       |      0
        /// Size > 0  |       v       |       0       |      v      // Expected must be 1
        ///
        int get_items_expected() const
        {
            return std::abs(type_size_ * expected_) *
                   ((multi_option_policy_ != MultiOptionPolicy::Throw || (expected_ < 0 && type_size_ < 0) ? -1 : 1));
        }

        /// True if the argument can be given directly
        bool get_positional() const { return pname_.length() > 0; }

        /// True if option has at least one non-positional name
        bool nonpositional() const { return (snames_.size() + lnames_.size()) > 0; }

        /// True if option has description
        bool has_description() const { return description_.length() > 0; }

        /// Get the description
        const std::string& get_description() const { return description_; }

        /// Set the description
        Option* description(std::string option_description)
        {
            description_ = std::move(option_description);
            return this;
        }

        ///@}
        /// @name Help tools
        ///@{

        /// \brief Gets a comma separated list of names.
        /// Will include / prefer the positional name if positional is true.
        /// If all_options is false, pick just the most descriptive name to show.
        /// Use `get_name(true)` to get the positional name (replaces `get_pname`)
        std::string get_name(bool positional = false, //<[input] Show the positional name
                             bool all_options = false //<[input] Show every option
                             ) const
        {
            if (all_options)
            {
                std::vector<std::string> name_list;

                /// The all list will never include a positional unless asked or that's the only name.
                if ((positional && pname_.length()) || (snames_.empty() && lnames_.empty()))
                    name_list.push_back(pname_);
                if ((get_items_expected() == 0) && (!fnames_.empty()))
                {
                    for (const std::string& sname : snames_)
                    {
                        name_list.push_back("-" + sname);
                        if (check_fname(sname))
                        {
                            name_list.back() += "{" + get_flag_value(sname, "") + "}";
                        }
                    }

                    for (const std::string& lname : lnames_)
                    {
                        name_list.push_back("--" + lname);
                        if (check_fname(lname))
                        {
                            name_list.back() += "{" + get_flag_value(lname, "") + "}";
                        }
                    }
                }
                else
                {
                    for (const std::string& sname : snames_)
                        name_list.push_back("-" + sname);

                    for (const std::string& lname : lnames_)
                        name_list.push_back("--" + lname);
                }

                return detail::join(name_list);
            }
            else
            {
                // This returns the positional name no matter what
                if (positional)
                    return pname_;

                // Prefer long name
                else if (!lnames_.empty())
                    return std::string("--") + lnames_[0];

                // Or short name if no long name
                else if (!snames_.empty())
                    return std::string("-") + snames_[0];

                // If positional is the only name, it's okay to use that
                else
                    return pname_;
            }
        }

        ///@}
        /// @name Parser tools
        ///@{

        /// Process the callback
        void run_callback()
        {
            callback_run_ = true;

            // Run the validators (can change the string)
            if (!validators_.empty())
            {
                for (std::string& result : results_)
                {
                    auto err_msg = _validate(result);
                    if (!err_msg.empty())
                        throw ValidationError(get_name(), err_msg);
                }
            }
            if (!(callback_))
            {
                return;
            }
            bool local_result;

            // Num items expected or length of vector, always at least 1
            // Only valid for a trimming policy
            int trim_size =
                std::min<int>(std::max<int>(std::abs(get_items_expected()), 1), static_cast<int>(results_.size()));

            // Operation depends on the policy setting
            if (multi_option_policy_ == MultiOptionPolicy::TakeLast)
            {
                // Allow multi-option sizes (including 0)
                results_t partial_result{ results_.end() - trim_size, results_.end() };
                local_result = !callback_(partial_result);
            }
            else if (multi_option_policy_ == MultiOptionPolicy::TakeFirst)
            {
                results_t partial_result{ results_.begin(), results_.begin() + trim_size };
                local_result = !callback_(partial_result);
            }
            else if (multi_option_policy_ == MultiOptionPolicy::Join)
            {
                results_t partial_result = { detail::join(results_, "\n") };
                local_result = !callback_(partial_result);
            }
            else
            {
                // Exact number required
                if (get_items_expected() > 0)
                {
                    if (results_.size() != static_cast<size_t>(get_items_expected()))
                        throw ArgumentMismatch(get_name(), get_items_expected(), results_.size());
                    // Variable length list
                }
                else if (get_items_expected() < 0)
                {
                    // Require that this be a multiple of expected size and at least as many as expected
                    if (results_.size() < static_cast<size_t>(-get_items_expected()) ||
                        results_.size() % static_cast<size_t>(std::abs(get_type_size())) != 0u)
                        throw ArgumentMismatch(get_name(), get_items_expected(), results_.size());
                }
                local_result = !callback_(results_);
            }

            if (local_result)
                throw ConversionError(get_name(), results_);
        }

        /// If options share any of the same names, they are equal (not counting positional)
        bool operator==(const Option& other) const
        {
            for (const std::string& sname : snames_)
                if (other.check_sname(sname))
                    return true;
            for (const std::string& lname : lnames_)
                if (other.check_lname(lname))
                    return true;

            if (ignore_case_ ||
                ignore_underscore_)
            { // We need to do the inverse, in case we are ignore_case or ignore underscore
                for (const std::string& sname : other.snames_)
                    if (check_sname(sname))
                        return true;
                for (const std::string& lname : other.lnames_)
                    if (check_lname(lname))
                        return true;
            }
            return false;
        }

        /// Check a name. Requires "-" or "--" for short / long, supports positional name
        bool check_name(std::string name) const
        {
            if (name.length() > 2 && name[0] == '-' && name[1] == '-')
                return check_lname(name.substr(2));
            else if (name.length() > 1 && name.front() == '-')
                return check_sname(name.substr(1));
            else
            {
                std::string local_pname = pname_;
                if (ignore_underscore_)
                {
                    local_pname = detail::remove_underscore(local_pname);
                    name = detail::remove_underscore(name);
                }
                if (ignore_case_)
                {
                    local_pname = detail::to_lower(local_pname);
                    name = detail::to_lower(name);
                }
                return name == local_pname;
            }
        }

        /// Requires "-" to be removed from string
        bool check_sname(std::string name) const { return (detail::find_member(name, snames_, ignore_case_) >= 0); }

        /// Requires "--" to be removed from string
        bool check_lname(std::string name) const
        {
            return (detail::find_member(name, lnames_, ignore_case_, ignore_underscore_) >= 0);
        }

        /// Requires "--" to be removed from string
        bool check_fname(std::string name) const
        {
            if (fnames_.empty())
            {
                return false;
            }
            return (detail::find_member(name, fnames_, ignore_case_, ignore_underscore_) >= 0);
        }

        std::string get_flag_value(std::string name, std::string input_value) const
        {
            static const std::string trueString{ "true" };
            static const std::string falseString{ "false" };
            static const std::string emptyString{ "{}" };
            // check for disable flag override_
            if (disable_flag_override_)
            {
                if (!((input_value.empty()) || (input_value == emptyString)))
                {
                    auto default_ind = detail::find_member(name, fnames_, ignore_case_, ignore_underscore_);
                    if (default_ind >= 0)
                    {
                        // We can static cast this to size_t because it is more than 0 in this block
                        if (default_flag_values_[static_cast<size_t>(default_ind)].second != input_value)
                        {
                            throw(ArgumentMismatch::FlagOverride(name));
                        }
                    }
                    else
                    {
                        if (input_value != trueString)
                        {
                            throw(ArgumentMismatch::FlagOverride(name));
                        }
                    }
                }
            }
            auto ind = detail::find_member(name, fnames_, ignore_case_, ignore_underscore_);
            if ((input_value.empty()) || (input_value == emptyString))
            {
                return (ind < 0) ? trueString : default_flag_values_[static_cast<size_t>(ind)].second;
            }
            if (ind < 0)
            {
                return input_value;
            }
            if (default_flag_values_[static_cast<size_t>(ind)].second == falseString)
            {
                try
                {
                    auto val = detail::to_flag_value(input_value);
                    return (val == 1) ? falseString : (val == (-1) ? trueString : std::to_string(-val));
                }
                catch (const std::invalid_argument&)
                {
                    return input_value;
                }
            }
            else
            {
                return input_value;
            }
        }

        /// Puts a result at the end
        Option* add_result(std::string s)
        {
            _add_result(std::move(s));
            callback_run_ = false;
            return this;
        }

        /// Puts a result at the end and get a count of the number of arguments actually added
        Option* add_result(std::string s, int& results_added)
        {
            results_added = _add_result(std::move(s));
            callback_run_ = false;
            return this;
        }

        /// Puts a result at the end
        Option* add_result(std::vector<std::string> s)
        {
            for (auto& str : s)
            {
                _add_result(std::move(str));
            }
            callback_run_ = false;
            return this;
        }

        /// Get a copy of the results
        std::vector<std::string> results() const { return results_; }

        /// get the results as a particular type
        template<typename T,
                 enable_if_t<!is_vector<T>::value && !std::is_const<T>::value, detail::enabler> = detail::dummy>
        void results(T& output) const
        {
            bool retval;
            if (results_.empty())
            {
                retval = detail::lexical_cast(default_str_, output);
            }
            else if (results_.size() == 1)
            {
                retval = detail::lexical_cast(results_[0], output);
            }
            else
            {
                switch (multi_option_policy_)
                {
                case MultiOptionPolicy::TakeFirst:
                    retval = detail::lexical_cast(results_.front(), output);
                    break;
                case MultiOptionPolicy::TakeLast:
                default:
                    retval = detail::lexical_cast(results_.back(), output);
                    break;
                case MultiOptionPolicy::Throw:
                    throw ConversionError(get_name(), results_);
                case MultiOptionPolicy::Join:
                    retval = detail::lexical_cast(detail::join(results_), output);
                    break;
                }
            }
            if (!retval)
            {
                throw ConversionError(get_name(), results_);
            }
        }
        /// get the results as a vector of a particular type
        template<typename T>
        void results(std::vector<T>& output) const
        {
            output.clear();
            bool retval = true;

            for (const auto& elem : results_)
            {
                output.emplace_back();
                retval &= detail::lexical_cast(elem, output.back());
            }

            if (!retval)
            {
                throw ConversionError(get_name(), results_);
            }
        }

        /// return the results as a particular type
        template<typename T>
        T as() const
        {
            T output;
            results(output);
            return output;
        }

        /// See if the callback has been run already
        bool get_callback_run() const { return callback_run_; }

        ///@}
        /// @name Custom options
        ///@{

        /// Set the type function to run when displayed on this option
        Option* type_name_fn(std::function<std::string()> typefun)
        {
            type_name_ = typefun;
            return this;
        }

        /// Set a custom option typestring
        Option* type_name(std::string typeval)
        {
            type_name_fn([typeval]() { return typeval; });
            return this;
        }

        /// Set a custom option size
        Option* type_size(int option_type_size)
        {
            type_size_ = option_type_size;
            if (type_size_ == 0)
                required_ = false;
            if (option_type_size < 0)
                expected_ = -1;
            return this;
        }

        /// Set a capture function for the default. Mostly used by App.
        Option* default_function(const std::function<std::string()>& func)
        {
            default_function_ = func;
            return this;
        }

        /// Capture the default value from the original value (if it can be captured)
        Option* capture_default_str()
        {
            if (default_function_)
            {
                default_str_ = default_function_();
            }
            return this;
        }

        /// Set the default value string representation (does not change the contained value)
        Option* default_str(std::string val)
        {
            default_str_ = val;
            return this;
        }

        /// Set the default value string representation and evaluate into the bound value
        Option* default_val(std::string val)
        {
            default_str(val);
            auto old_results = results_;
            results_ = { val };
            run_callback();
            results_ = std::move(old_results);
            return this;
        }

        /// Get the full typename for this option
        std::string get_type_name() const
        {
            std::string full_type_name = type_name_();
            if (!validators_.empty())
            {
                for (auto& validator : validators_)
                {
                    std::string vtype = validator.get_description();
                    if (!vtype.empty())
                    {
                        full_type_name += ":" + vtype;
                    }
                }
            }
            return full_type_name;
        }

    private:
        // run through the validators
        std::string _validate(std::string& result)
        {
            std::string err_msg;
            for (const auto& vali : validators_)
            {
                try
                {
                    err_msg = vali(result);
                }
                catch (const ValidationError& err)
                {
                    err_msg = err.what();
                }
                if (!err_msg.empty())
                    break;
            }
            return err_msg;
        }

        int _add_result(std::string&& result)
        {
            int result_count = 0;
            if (delimiter_ == '\0')
            {
                results_.push_back(std::move(result));
                ++result_count;
            }
            else
            {
                if ((result.find_first_of(delimiter_) != std::string::npos))
                {
                    for (const auto& var : CLI::detail::split(result, delimiter_))
                    {
                        if (!var.empty())
                        {
                            results_.push_back(var);
                            ++result_count;
                        }
                    }
                }
                else
                {
                    results_.push_back(std::move(result));
                    ++result_count;
                }
            }
            return result_count;
        }
    };

} // namespace CLI

// From CLI/App.hpp:

namespace CLI
{
#ifndef CLI11_PARSE
#define CLI11_PARSE(app, argc, argv) \
    try                              \
    {                                \
        (app).parse((argc), (argv)); \
    }                                \
    catch (const CLI::ParseError& e) \
    {                                \
        return (app).exit(e);        \
    }
#endif

    namespace detail
    {
        enum class Classifier
        {
            NONE,
            POSITIONAL_MARK,
            SHORT,
            LONG,
            WINDOWS,
            SUBCOMMAND,
            SUBCOMMAND_TERMINATOR
        };
        struct AppFriend;
    } // namespace detail

    namespace FailureMessage
    {
        std::string simple(const App* app, const Error& e);
        std::string help(const App* app, const Error& e);
    } // namespace FailureMessage

    class App;

    using App_p = std::shared_ptr<App>;

    class Option_group;
    /// Creates a command line program, with very few defaults.
    /** To use, create a new `Program()` instance with `argc`, `argv`, and a help description. The templated
 *  add_option methods make it easy to prepare options. Remember to call `.start` before starting your
 * program, so that the options can be evaluated and the help option doesn't accidentally run your program. */
    class App
    {
        friend Option;
        friend detail::AppFriend;

    protected:
        // This library follows the Google style guide for member names ending in underscores

        /// @name Basics
        ///@{

        /// Subcommand name or program name (from parser if name is empty)
        std::string name_;

        /// Description of the current program/subcommand
        std::string description_;

        /// If true, allow extra arguments (ie, don't throw an error). INHERITABLE
        bool allow_extras_{ false };

        /// If true, allow extra arguments in the ini file (ie, don't throw an error). INHERITABLE
        bool allow_config_extras_{ false };

        ///  If true, return immediately on an unrecognized option (implies allow_extras) INHERITABLE
        bool prefix_command_{ false };

        /// If set to true the name was automatically generated from the command line vs a user set name
        bool has_automatic_name_{ false };

        /// If set to true the subcommand is required to be processed and used, ignored for main app
        bool required_{ false };

        /// If set to true the subcommand is disabled and cannot be used, ignored for main app
        bool disabled_{ false };

        /// Flag indicating that the pre_parse_callback has been triggered
        bool pre_parse_called_{ false };

        /// Flag indicating that the callback for the subcommand should be executed immediately on parse completion which is
        /// before help or ini files are processed. INHERITABLE
        bool immediate_callback_{ false };

        /// This is a function that runs prior to the start of parsing
        std::function<void(size_t)> pre_parse_callback_;

        /// This is a function that runs when complete. Great for subcommands. Can throw.
        std::function<void()> callback_;

        ///@}
        /// @name Options
        ///@{

        /// The default values for options, customizable and changeable INHERITABLE
        OptionDefaults option_defaults_;

        /// The list of options, stored locally
        std::vector<Option_p> options_;

        ///@}
        /// @name Help
        ///@{

        /// Footer to put after all options in the help output INHERITABLE
        std::string footer_;

        /// A pointer to the help flag if there is one INHERITABLE
        Option* help_ptr_{ nullptr };

        /// A pointer to the help all flag if there is one INHERITABLE
        Option* help_all_ptr_{ nullptr };

        /// This is the formatter for help printing. Default provided. INHERITABLE (same pointer)
        std::shared_ptr<FormatterBase> formatter_{ new Formatter() };

        /// The error message printing function INHERITABLE
        std::function<std::string(const App*, const Error& e)> failure_message_ = FailureMessage::simple;

        ///@}
        /// @name Parsing
        ///@{

        using missing_t = std::vector<std::pair<detail::Classifier, std::string>>;

        /// Pair of classifier, string for missing options. (extra detail is removed on returning from parse)
        ///
        /// This is faster and cleaner than storing just a list of strings and reparsing. This may contain the -- separator.
        missing_t missing_;

        /// This is a list of pointers to options with the original parse order
        std::vector<Option*> parse_order_;

        /// This is a list of the subcommands collected, in order
        std::vector<App*> parsed_subcommands_;

        /// this is a list of subcommands that are exclusionary to this one
        std::set<App*> exclude_subcommands_;

        /// This is a list of options which are exclusionary to this App, if the options were used this subcommand should
        /// not be
        std::set<Option*> exclude_options_;

        ///@}
        /// @name Subcommands
        ///@{

        /// Storage for subcommand list
        std::vector<App_p> subcommands_;

        /// If true, the program name is not case sensitive INHERITABLE
        bool ignore_case_{ false };

        /// If true, the program should ignore underscores INHERITABLE
        bool ignore_underscore_{ false };

        /// Allow subcommand fallthrough, so that parent commands can collect commands after subcommand.  INHERITABLE
        bool fallthrough_{ false };

        /// Allow '/' for options for Windows like options. Defaults to true on Windows, false otherwise. INHERITABLE
        bool allow_windows_style_options_{
#ifdef _WIN32
            true
#else
            false
#endif
        };
        /// specify that positional arguments come at the end of the argument sequence not inheritable
        bool positionals_at_end_{ false };

        /// If set to true the subcommand will start each parse disabled
        bool disabled_by_default_{ false };
        /// If set to true the subcommand will be reenabled at the start of each parse
        bool enabled_by_default_{ false };
        /// If set to true positional options are validated before assigning INHERITABLE
        bool validate_positionals_{ false };
        /// A pointer to the parent if this is a subcommand
        App* parent_{ nullptr };

        /// Counts the number of times this command/subcommand was parsed
        size_t parsed_ = 0;

        /// Minimum required subcommands (not inheritable!)
        size_t require_subcommand_min_ = 0;

        /// Max number of subcommands allowed (parsing stops after this number). 0 is unlimited INHERITABLE
        size_t require_subcommand_max_ = 0;

        /// Minimum required options (not inheritable!)
        size_t require_option_min_ = 0;

        /// Max number of options allowed. 0 is unlimited (not inheritable)
        size_t require_option_max_ = 0;

        /// The group membership INHERITABLE
        std::string group_{ "Subcommands" };

        ///@}
        /// @name Config
        ///@{

        /// The name of the connected config file
        std::string config_name_;

        /// True if ini is required (throws if not present), if false simply keep going.
        bool config_required_{ false };

        /// Pointer to the config option
        Option* config_ptr_{ nullptr };

        /// This is the formatter for help printing. Default provided. INHERITABLE (same pointer)
        std::shared_ptr<Config> config_formatter_{ new ConfigINI() };

        ///@}

        /// Special private constructor for subcommand
        App(std::string app_description, std::string app_name, App* parent) :
            name_(std::move(app_name)),
            description_(std::move(app_description)),
            parent_(parent)
        {
            // Inherit if not from a nullptr
            if (parent_ != nullptr)
            {
                if (parent_->help_ptr_ != nullptr)
                    set_help_flag(parent_->help_ptr_->get_name(false, true), parent_->help_ptr_->get_description());
                if (parent_->help_all_ptr_ != nullptr)
                    set_help_all_flag(parent_->help_all_ptr_->get_name(false, true),
                                      parent_->help_all_ptr_->get_description());

                /// OptionDefaults
                option_defaults_ = parent_->option_defaults_;

                // INHERITABLE
                failure_message_ = parent_->failure_message_;
                allow_extras_ = parent_->allow_extras_;
                allow_config_extras_ = parent_->allow_config_extras_;
                prefix_command_ = parent_->prefix_command_;
                immediate_callback_ = parent_->immediate_callback_;
                ignore_case_ = parent_->ignore_case_;
                ignore_underscore_ = parent_->ignore_underscore_;
                fallthrough_ = parent_->fallthrough_;
                validate_positionals_ = parent_->validate_positionals_;
                allow_windows_style_options_ = parent_->allow_windows_style_options_;
                group_ = parent_->group_;
                footer_ = parent_->footer_;
                formatter_ = parent_->formatter_;
                config_formatter_ = parent_->config_formatter_;
                require_subcommand_max_ = parent_->require_subcommand_max_;
            }
        }

    public:
        /// @name Basic
        ///@{

        /// Create a new program. Pass in the same arguments as main(), along with a help string.
        explicit App(std::string app_description = "", std::string app_name = "") :
            App(app_description, app_name, nullptr)
        {
            set_help_flag("-h,--help", "Print this help message and exit");
        }

        /// virtual destructor
        virtual ~App() = default;

        /// Set a callback for the end of parsing.
        ///
        /// Due to a bug in c++11,
        /// it is not possible to overload on std::function (fixed in c++14
        /// and backported to c++11 on newer compilers). Use capture by reference
        /// to get a pointer to App if needed.
        App* callback(std::function<void()> app_callback)
        {
            callback_ = std::move(app_callback);
            return this;
        }

        /// Set a callback to execute prior to parsing.
        ///
        App* preparse_callback(std::function<void(size_t)> pp_callback)
        {
            pre_parse_callback_ = std::move(pp_callback);
            return this;
        }

        /// Set a name for the app (empty will use parser to set the name)
        App* name(std::string app_name = "")
        {
            name_ = app_name;
            has_automatic_name_ = false;
            return this;
        }

        /// Remove the error when extras are left over on the command line.
        App* allow_extras(bool allow = true)
        {
            allow_extras_ = allow;
            return this;
        }

        /// Remove the error when extras are left over on the command line.
        App* required(bool require = true)
        {
            required_ = require;
            return this;
        }

        /// Disable the subcommand or option group
        App* disabled(bool disable = true)
        {
            disabled_ = disable;
            return this;
        }

        /// Set the subcommand to be disabled by default, so on clear(), at the start of each parse it is disabled
        App* disabled_by_default(bool disable = true)
        {
            disabled_by_default_ = disable;
            return this;
        }

        /// Set the subcommand to be enabled by default, so on clear(), at the start of each parse it is enabled (not
        /// disabled)
        App* enabled_by_default(bool enable = true)
        {
            enabled_by_default_ = enable;
            return this;
        }

        /// Set the subcommand callback to be executed immediately on subcommand completion
        App* immediate_callback(bool immediate = true)
        {
            immediate_callback_ = immediate;
            return this;
        }

        /// Set the subcommand to validate positional arguments before assigning
        App* validate_positionals(bool validate = true)
        {
            validate_positionals_ = validate;
            return this;
        }

        /// Remove the error when extras are left over on the command line.
        /// Will also call App::allow_extras().
        App* allow_config_extras(bool allow = true)
        {
            allow_extras(allow);
            allow_config_extras_ = allow;
            return this;
        }

        /// Do not parse anything after the first unrecognized option and return
        App* prefix_command(bool allow = true)
        {
            prefix_command_ = allow;
            return this;
        }

        /// Ignore case. Subcommands inherit value.
        App* ignore_case(bool value = true)
        {
            ignore_case_ = value;
            if (parent_ != nullptr && !name_.empty())
            {
                for (const auto& subc : parent_->subcommands_)
                {
                    if (subc.get() != this && (this->check_name(subc->name_) || subc->check_name(this->name_)))
                        throw OptionAlreadyAdded(subc->name_);
                }
            }
            return this;
        }

        /// Allow windows style options, such as `/opt`. First matching short or long name used. Subcommands inherit value.
        App* allow_windows_style_options(bool value = true)
        {
            allow_windows_style_options_ = value;
            return this;
        }

        /// Specify that the positional arguments are only at the end of the sequence
        App* positionals_at_end(bool value = true)
        {
            positionals_at_end_ = value;
            return this;
        }

        /// Ignore underscore. Subcommands inherit value.
        App* ignore_underscore(bool value = true)
        {
            ignore_underscore_ = value;
            if (parent_ != nullptr && !name_.empty())
            {
                for (const auto& subc : parent_->subcommands_)
                {
                    if (subc.get() != this && (this->check_name(subc->name_) || subc->check_name(this->name_)))
                        throw OptionAlreadyAdded(subc->name_);
                }
            }
            return this;
        }

        /// Set the help formatter
        App* formatter(std::shared_ptr<FormatterBase> fmt)
        {
            formatter_ = fmt;
            return this;
        }

        /// Set the help formatter
        App* formatter_fn(std::function<std::string(const App*, std::string, AppFormatMode)> fmt)
        {
            formatter_ = std::make_shared<FormatterLambda>(fmt);
            return this;
        }

        /// Set the config formatter
        App* config_formatter(std::shared_ptr<Config> fmt)
        {
            config_formatter_ = fmt;
            return this;
        }

        /// Check to see if this subcommand was parsed, true only if received on command line.
        bool parsed() const { return parsed_ > 0; }

        /// Get the OptionDefault object, to set option defaults
        OptionDefaults* option_defaults() { return &option_defaults_; }

        ///@}
        /// @name Adding options
        ///@{

        /// Add an option, will automatically understand the type for common types.
        ///
        /// To use, create a variable with the expected type, and pass it in after the name.
        /// After start is called, you can use count to see if the value was passed, and
        /// the value will be initialized properly. Numbers, vectors, and strings are supported.
        ///
        /// ->required(), ->default, and the validators are options,
        /// The positional options take an optional number of arguments.
        ///
        /// For example,
        ///
        ///     std::string filename;
        ///     program.add_option("filename", filename, "description of filename");
        ///
        Option* add_option(std::string option_name,
                           callback_t option_callback,
                           std::string option_description = "",
                           bool defaulted = false,
                           std::function<std::string()> func = {})
        {
            Option myopt{ option_name, option_description, option_callback, this };

            if (std::find_if(std::begin(options_), std::end(options_), [&myopt](const Option_p& v) {
                    return *v == myopt;
                }) == std::end(options_))
            {
                options_.emplace_back();
                Option_p& option = options_.back();
                option.reset(new Option(option_name, option_description, option_callback, this));

                // Set the default string capture function
                option->default_function(func);

                // For compatibility with CLI11 1.7 and before, capture the default string here
                if (defaulted)
                    option->capture_default_str();

                // Transfer defaults to the new option
                option_defaults_.copy_to(option.get());

                // Don't bother to capture if we already did
                if (!defaulted && option->get_always_capture_default())
                    option->capture_default_str();

                return option.get();
            }
            else
                throw OptionAlreadyAdded(myopt.get_name());
        }

        /// Add option for non-vectors (duplicate copy needed without defaulted to avoid `iostream << value`)
        template<typename T, enable_if_t<!is_vector<T>::value & !std::is_const<T>::value, detail::enabler> = detail::dummy>
        Option* add_option(std::string option_name,
                           T& variable, ///< The variable to set
                           std::string option_description = "",
                           bool defaulted = false)
        {
            auto fun = [&variable](CLI::results_t res) { return detail::lexical_cast(res[0], variable); };

            Option* opt = add_option(option_name, fun, option_description, defaulted, [&variable]() {
                return std::string(CLI::detail::to_string(variable));
            });
            opt->type_name(detail::type_name<T>());

            return opt;
        }

        /// Add option for a callback of a specific type
        template<typename T, enable_if_t<!is_vector<T>::value, detail::enabler> = detail::dummy>
        Option* add_option_function(std::string option_name,
                                    const std::function<void(const T&)>& func, ///< the callback to execute
                                    std::string option_description = "")
        {
            auto fun = [func](CLI::results_t res) {
                T variable;
                bool result = detail::lexical_cast(res[0], variable);
                if (result)
                {
                    func(variable);
                }
                return result;
            };

            Option* opt = add_option(option_name, std::move(fun), option_description, false);
            opt->type_name(detail::type_name<T>());
            return opt;
        }

        /// Add option with no description or variable assignment
        Option* add_option(std::string option_name)
        {
            return add_option(option_name, CLI::callback_t(), std::string{}, false);
        }

        /// Add option with description but with no variable assignment or callback
        template<typename T,
                 enable_if_t<std::is_const<T>::value && std::is_constructible<std::string, T>::value, detail::enabler> =
                     detail::dummy>
        Option* add_option(std::string option_name, T& option_description)
        {
            return add_option(option_name, CLI::callback_t(), option_description, false);
        }

        /// Add option for vectors
        template<typename T>
        Option* add_option(std::string option_name,
                           std::vector<T>& variable, ///< The variable vector to set
                           std::string option_description = "",
                           bool defaulted = false)
        {
            auto fun = [&variable](CLI::results_t res) {
                bool retval = true;
                variable.clear();
                variable.reserve(res.size());
                for (const auto& elem : res)
                {
                    variable.emplace_back();
                    retval &= detail::lexical_cast(elem, variable.back());
                }
                return (!variable.empty()) && retval;
            };

            auto default_function = [&variable]() {
                std::vector<std::string> defaults;
                defaults.resize(variable.size());
                std::transform(variable.begin(), variable.end(), defaults.begin(), [](T& val) {
                    return std::string(CLI::detail::to_string(val));
                });
                return std::string("[" + detail::join(defaults) + "]");
            };

            Option* opt = add_option(option_name, fun, option_description, defaulted, default_function);
            opt->type_name(detail::type_name<T>())->type_size(-1);

            return opt;
        }

        /// Add option for a vector callback of a specific type
        template<typename T, enable_if_t<is_vector<T>::value, detail::enabler> = detail::dummy>
        Option* add_option_function(std::string option_name,
                                    const std::function<void(const T&)>& func, ///< the callback to execute
                                    std::string option_description = "")
        {
            CLI::callback_t fun = [func](CLI::results_t res) {
                T values;
                bool retval = true;
                values.reserve(res.size());
                for (const auto& elem : res)
                {
                    values.emplace_back();
                    retval &= detail::lexical_cast(elem, values.back());
                }
                if (retval)
                {
                    func(values);
                }
                return retval;
            };

            Option* opt = add_option(option_name, std::move(fun), std::move(option_description), false);
            opt->type_name(detail::type_name<T>())->type_size(-1);
            return opt;
        }

        /// Set a help flag, replace the existing one if present
        Option* set_help_flag(std::string flag_name = "", const std::string& help_description = "")
        {
            // take flag_description by const reference otherwise add_flag tries to assign to help_description
            if (help_ptr_ != nullptr)
            {
                remove_option(help_ptr_);
                help_ptr_ = nullptr;
            }

            // Empty name will simply remove the help flag
            if (!flag_name.empty())
            {
                help_ptr_ = add_flag(flag_name, help_description);
                help_ptr_->configurable(false);
            }

            return help_ptr_;
        }

        /// Set a help all flag, replaced the existing one if present
        Option* set_help_all_flag(std::string help_name = "", const std::string& help_description = "")
        {
            // take flag_description by const reference otherwise add_flag tries to assign to flag_description
            if (help_all_ptr_ != nullptr)
            {
                remove_option(help_all_ptr_);
                help_all_ptr_ = nullptr;
            }

            // Empty name will simply remove the help all flag
            if (!help_name.empty())
            {
                help_all_ptr_ = add_flag(help_name, help_description);
                help_all_ptr_->configurable(false);
            }

            return help_all_ptr_;
        }

    private:
        /// Internal function for adding a flag
        Option* _add_flag_internal(std::string flag_name, CLI::callback_t fun, std::string flag_description)
        {
            Option* opt;
            if (detail::has_default_flag_values(flag_name))
            {
                // check for default values and if it has them
                auto flag_defaults = detail::get_default_flag_values(flag_name);
                detail::remove_default_flag_values(flag_name);
                opt = add_option(std::move(flag_name), std::move(fun), std::move(flag_description), false);
                for (const auto& fname : flag_defaults)
                    opt->fnames_.push_back(fname.first);
                opt->default_flag_values_ = std::move(flag_defaults);
            }
            else
            {
                opt = add_option(std::move(flag_name), std::move(fun), std::move(flag_description), false);
            }
            // flags cannot have positional values
            if (opt->get_positional())
            {
                auto pos_name = opt->get_name(true);
                remove_option(opt);
                throw IncorrectConstruction::PositionalFlag(pos_name);
            }

            opt->type_size(0);
            return opt;
        }

    public:
        /// Add a flag with no description or variable assignment
        Option* add_flag(std::string flag_name) { return _add_flag_internal(flag_name, CLI::callback_t(), std::string{}); }

        /// Add flag with description but with no variable assignment or callback
        /// takes a constant string,  if a variable string is passed that variable will be assigned the results from the
        /// flag
        template<typename T,
                 enable_if_t<std::is_const<T>::value && std::is_constructible<std::string, T>::value, detail::enabler> =
                     detail::dummy>
        Option* add_flag(std::string flag_name, T& flag_description)
        {
            return _add_flag_internal(flag_name, CLI::callback_t(), flag_description);
        }

        /// Add option for flag with integer result - defaults to allowing multiple passings, but can be forced to one if
        /// `multi_option_policy(CLI::MultiOptionPolicy::Throw)` is used.
        template<typename T,
                 enable_if_t<std::is_integral<T>::value && !is_bool<T>::value, detail::enabler> = detail::dummy>
        Option* add_flag(std::string flag_name,
                         T& flag_count, ///< A variable holding the count
                         std::string flag_description = "")
        {
            flag_count = 0;
            CLI::callback_t fun = [&flag_count](CLI::results_t res) {
                try
                {
                    detail::sum_flag_vector(res, flag_count);
                }
                catch (const std::invalid_argument&)
                {
                    return false;
                }
                return true;
            };
            return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description));
        }

        /// Other type version accepts all other types that are not vectors such as bool, enum, string or other classes that
        /// can be converted from a string
        template<typename T,
                 enable_if_t<!is_vector<T>::value && !std::is_const<T>::value &&
                                 (!std::is_integral<T>::value || is_bool<T>::value) &&
                                 !std::is_constructible<std::function<void(int)>, T>::value,
                             detail::enabler> = detail::dummy>
        Option* add_flag(std::string flag_name,
                         T& flag_result, ///< A variable holding true if passed
                         std::string flag_description = "")
        {
            CLI::callback_t fun = [&flag_result](CLI::results_t res) {
                if (res.size() != 1)
                {
                    return false;
                }
                return CLI::detail::lexical_cast(res[0], flag_result);
            };
            Option* opt = _add_flag_internal(flag_name, std::move(fun), std::move(flag_description));
            opt->multi_option_policy(CLI::MultiOptionPolicy::TakeLast);
            return opt;
        }

        /// Vector version to capture multiple flags.
        template<typename T,
                 enable_if_t<!std::is_assignable<std::function<void(int64_t)>, T>::value, detail::enabler> = detail::dummy>
        Option* add_flag(std::string flag_name,
                         std::vector<T>& flag_results, ///< A vector of values with the flag results
                         std::string flag_description = "")
        {
            CLI::callback_t fun = [&flag_results](CLI::results_t res) {
                bool retval = true;
                for (const auto& elem : res)
                {
                    flag_results.emplace_back();
                    retval &= detail::lexical_cast(elem, flag_results.back());
                }
                return retval;
            };
            return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description));
        }

        /// Add option for callback that is triggered with a true flag and takes no arguments
        Option* add_flag_callback(std::string flag_name,
                                  std::function<void(void)> function, ///< A function to call, void(void)
                                  std::string flag_description = "")
        {
            CLI::callback_t fun = [function](CLI::results_t res) {
                if (res.size() != 1)
                {
                    return false;
                }
                bool trigger;
                auto result = CLI::detail::lexical_cast(res[0], trigger);
                if (trigger)
                    function();
                return result;
            };
            Option* opt = _add_flag_internal(flag_name, std::move(fun), std::move(flag_description));
            opt->multi_option_policy(CLI::MultiOptionPolicy::TakeLast);
            return opt;
        }

        /// Add option for callback with an integer value
        Option* add_flag_function(std::string flag_name,
                                  std::function<void(int64_t)> function, ///< A function to call, void(int)
                                  std::string flag_description = "")
        {
            CLI::callback_t fun = [function](CLI::results_t res) {
                int64_t flag_count = 0;
                detail::sum_flag_vector(res, flag_count);
                function(flag_count);
                return true;
            };
            return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description));
        }

#ifdef CLI11_CPP14
        /// Add option for callback (C++14 or better only)
        Option* add_flag(std::string flag_name,
                         std::function<void(int64_t)> function, ///< A function to call, void(int64_t)
                         std::string flag_description = "")
        {
            return add_flag_function(std::move(flag_name), std::move(function), std::move(flag_description));
        }
#endif

        /// Add set of options (No default, temp reference, such as an inline set) DEPRECATED
        template<typename T>
        Option* add_set(std::string option_name,
                        T& member, ///< The selected member of the set
                        std::set<T> options, ///< The set of possibilities
                        std::string option_description = "")
        {
            Option* opt = add_option(option_name, member, std::move(option_description));
            opt->check(IsMember{ options });
            return opt;
        }

        /// Add set of options (No default, set can be changed afterwards - do not destroy the set) DEPRECATED
        template<typename T>
        Option* add_mutable_set(std::string option_name,
                                T& member, ///< The selected member of the set
                                const std::set<T>& options, ///< The set of possibilities
                                std::string option_description = "")
        {
            Option* opt = add_option(option_name, member, std::move(option_description));
            opt->check(IsMember{ &options });
            return opt;
        }

        /// Add set of options (with default, static set, such as an inline set) DEPRECATED
        template<typename T>
        Option* add_set(std::string option_name,
                        T& member, ///< The selected member of the set
                        std::set<T> options, ///< The set of possibilities
                        std::string option_description,
                        bool defaulted)
        {
            Option* opt = add_option(option_name, member, std::move(option_description), defaulted);
            opt->check(IsMember{ options });
            return opt;
        }

        /// Add set of options (with default, set can be changed afterwards - do not destroy the set) DEPRECATED
        template<typename T>
        Option* add_mutable_set(std::string option_name,
                                T& member, ///< The selected member of the set
                                const std::set<T>& options, ///< The set of possibilities
                                std::string option_description,
                                bool defaulted)
        {
            Option* opt = add_option(option_name, member, std::move(option_description), defaulted);
            opt->check(IsMember{ &options });
            return opt;
        }

        /// Add set of options, string only, ignore case (no default, static set) DEPRECATED
        CLI11_DEPRECATED("Use ->transform(CLI::IsMember(..., CLI::ignore_case)) instead")
        Option* add_set_ignore_case(std::string option_name,
                                    std::string& member, ///< The selected member of the set
                                    std::set<std::string> options, ///< The set of possibilities
                                    std::string option_description = "")
        {
            Option* opt = add_option(option_name, member, std::move(option_description));
            opt->transform(IsMember{ options, CLI::ignore_case });
            return opt;
        }

        /// Add set of options, string only, ignore case (no default, set can be changed afterwards - do not destroy the
        /// set) DEPRECATED
        CLI11_DEPRECATED("Use ->transform(CLI::IsMember(..., CLI::ignore_case)) with a (shared) pointer instead")
        Option* add_mutable_set_ignore_case(std::string option_name,
                                            std::string& member, ///< The selected member of the set
                                            const std::set<std::string>& options, ///< The set of possibilities
                                            std::string option_description = "")
        {
            Option* opt = add_option(option_name, member, std::move(option_description));
            opt->transform(IsMember{ &options, CLI::ignore_case });
            return opt;
        }

        /// Add set of options, string only, ignore case (default, static set) DEPRECATED
        CLI11_DEPRECATED("Use ->transform(CLI::IsMember(..., CLI::ignore_case)) instead")
        Option* add_set_ignore_case(std::string option_name,
                                    std::string& member, ///< The selected member of the set
                                    std::set<std::string> options, ///< The set of possibilities
                                    std::string option_description,
                                    bool defaulted)
        {
            Option* opt = add_option(option_name, member, std::move(option_description), defaulted);
            opt->transform(IsMember{ options, CLI::ignore_case });
            return opt;
        }

        /// Add set of options, string only, ignore case (default, set can be changed afterwards - do not destroy the set)
        /// DEPRECATED
        CLI11_DEPRECATED("Use ->transform(CLI::IsMember(...)) with a (shared) pointer instead")
        Option* add_mutable_set_ignore_case(std::string option_name,
                                            std::string& member, ///< The selected member of the set
                                            const std::set<std::string>& options, ///< The set of possibilities
                                            std::string option_description,
                                            bool defaulted)
        {
            Option* opt = add_option(option_name, member, std::move(option_description), defaulted);
            opt->transform(IsMember{ &options, CLI::ignore_case });
            return opt;
        }

        /// Add set of options, string only, ignore underscore (no default, static set) DEPRECATED
        CLI11_DEPRECATED("Use ->transform(CLI::IsMember(..., CLI::ignore_underscore)) instead")
        Option* add_set_ignore_underscore(std::string option_name,
                                          std::string& member, ///< The selected member of the set
                                          std::set<std::string> options, ///< The set of possibilities
                                          std::string option_description = "")
        {
            Option* opt = add_option(option_name, member, std::move(option_description));
            opt->transform(IsMember{ options, CLI::ignore_underscore });
            return opt;
        }

        /// Add set of options, string only, ignore underscore (no default, set can be changed afterwards - do not destroy
        /// the set) DEPRECATED
        CLI11_DEPRECATED("Use ->transform(CLI::IsMember(..., CLI::ignore_underscore)) with a (shared) pointer instead")
        Option* add_mutable_set_ignore_underscore(std::string option_name,
                                                  std::string& member, ///< The selected member of the set
                                                  const std::set<std::string>& options, ///< The set of possibilities
                                                  std::string option_description = "")
        {
            Option* opt = add_option(option_name, member, std::move(option_description));
            opt->transform(IsMember{ options, CLI::ignore_underscore });
            return opt;
        }

        /// Add set of options, string only, ignore underscore (default, static set) DEPRECATED
        CLI11_DEPRECATED("Use ->transform(CLI::IsMember(..., CLI::ignore_underscore)) instead")
        Option* add_set_ignore_underscore(std::string option_name,
                                          std::string& member, ///< The selected member of the set
                                          std::set<std::string> options, ///< The set of possibilities
                                          std::string option_description,
                                          bool defaulted)
        {
            Option* opt = add_option(option_name, member, std::move(option_description), defaulted);
            opt->transform(IsMember{ options, CLI::ignore_underscore });
            return opt;
        }

        /// Add set of options, string only, ignore underscore (default, set can be changed afterwards - do not destroy the
        /// set) DEPRECATED
        CLI11_DEPRECATED("Use ->transform(CLI::IsMember(..., CLI::ignore_underscore)) with a (shared) pointer instead")
        Option* add_mutable_set_ignore_underscore(std::string option_name,
                                                  std::string& member, ///< The selected member of the set
                                                  const std::set<std::string>& options, ///< The set of possibilities
                                                  std::string option_description,
                                                  bool defaulted)
        {
            Option* opt = add_option(option_name, member, std::move(option_description), defaulted);
            opt->transform(IsMember{ &options, CLI::ignore_underscore });
            return opt;
        }

        /// Add set of options, string only, ignore underscore and case (no default, static set) DEPRECATED
        CLI11_DEPRECATED("Use ->transform(CLI::IsMember(..., CLI::ignore_case, CLI::ignore_underscore)) instead")
        Option* add_set_ignore_case_underscore(std::string option_name,
                                               std::string& member, ///< The selected member of the set
                                               std::set<std::string> options, ///< The set of possibilities
                                               std::string option_description = "")
        {
            Option* opt = add_option(option_name, member, std::move(option_description));
            opt->transform(IsMember{ options, CLI::ignore_underscore, CLI::ignore_case });
            return opt;
        }

        /// Add set of options, string only, ignore underscore and case (no default, set can be changed afterwards - do not
        /// destroy the set) DEPRECATED
        CLI11_DEPRECATED(
            "Use ->transform(CLI::IsMember(..., CLI::ignore_case, CLI::ignore_underscore)) with a (shared) pointer instead")
        Option* add_mutable_set_ignore_case_underscore(std::string option_name,
                                                       std::string& member, ///< The selected member of the set
                                                       const std::set<std::string>& options, ///< The set of possibilities
                                                       std::string option_description = "")
        {
            Option* opt = add_option(option_name, member, std::move(option_description));
            opt->transform(IsMember{ &options, CLI::ignore_underscore, CLI::ignore_case });
            return opt;
        }

        /// Add set of options, string only, ignore underscore and case (default, static set) DEPRECATED
        CLI11_DEPRECATED("Use ->transform(CLI::IsMember(..., CLI::ignore_case, CLI::ignore_underscore)) instead")
        Option* add_set_ignore_case_underscore(std::string option_name,
                                               std::string& member, ///< The selected member of the set
                                               std::set<std::string> options, ///< The set of possibilities
                                               std::string option_description,
                                               bool defaulted)
        {
            Option* opt = add_option(option_name, member, std::move(option_description), defaulted);
            opt->transform(IsMember{ options, CLI::ignore_underscore, CLI::ignore_case });
            return opt;
        }

        /// Add set of options, string only, ignore underscore and case (default, set can be changed afterwards - do not
        /// destroy the set) DEPRECATED
        CLI11_DEPRECATED(
            "Use ->transform(CLI::IsMember(..., CLI::ignore_case, CLI::ignore_underscore)) with a (shared) pointer instead")
        Option* add_mutable_set_ignore_case_underscore(std::string option_name,
                                                       std::string& member, ///< The selected member of the set
                                                       const std::set<std::string>& options, ///< The set of possibilities
                                                       std::string option_description,
                                                       bool defaulted)
        {
            Option* opt = add_option(option_name, member, std::move(option_description), defaulted);
            opt->transform(IsMember{ &options, CLI::ignore_underscore, CLI::ignore_case });
            return opt;
        }

        /// Add a complex number
        template<typename T>
        Option* add_complex(std::string option_name,
                            T& variable,
                            std::string option_description = "",
                            bool defaulted = false,
                            std::string label = "COMPLEX")
        {
            std::string simple_name = CLI::detail::split(option_name, ',').at(0);
            CLI::callback_t fun = [&variable, simple_name, label](results_t res) {
                if (res[1].back() == 'i')
                    res[1].pop_back();
                double x, y;
                bool worked = detail::lexical_cast(res[0], x) && detail::lexical_cast(res[1], y);
                if (worked)
                    variable = T(x, y);
                return worked;
            };

            auto default_function = [&variable]() {
                std::stringstream out;
                out << variable;
                return out.str();
            };

            CLI::Option* opt =
                add_option(option_name, std::move(fun), std::move(option_description), defaulted, default_function);

            opt->type_name(label)->type_size(2);
            return opt;
        }

        /// Set a configuration ini file option, or clear it if no name passed
        Option* set_config(std::string option_name = "",
                           std::string default_filename = "",
                           std::string help_message = "Read an ini file",
                           bool config_required = false)
        {
            // Remove existing config if present
            if (config_ptr_ != nullptr)
                remove_option(config_ptr_);

            // Only add config if option passed
            if (!option_name.empty())
            {
                config_name_ = default_filename;
                config_required_ = config_required;
                config_ptr_ = add_option(option_name, config_name_, help_message, !default_filename.empty());
                config_ptr_->configurable(false);
            }

            return config_ptr_;
        }

        /// Removes an option from the App. Takes an option pointer. Returns true if found and removed.
        bool remove_option(Option* opt)
        {
            // Make sure no links exist
            for (Option_p& op : options_)
            {
                op->remove_needs(opt);
                op->remove_excludes(opt);
            }

            if (help_ptr_ == opt)
                help_ptr_ = nullptr;
            if (help_all_ptr_ == opt)
                help_all_ptr_ = nullptr;

            auto iterator =
                std::find_if(std::begin(options_), std::end(options_), [opt](const Option_p& v) { return v.get() == opt; });
            if (iterator != std::end(options_))
            {
                options_.erase(iterator);
                return true;
            }
            return false;
        }

        /// creates an option group as part of the given app
        template<typename T = Option_group>
        T* add_option_group(std::string group_name, std::string group_description = "")
        {
            auto option_group = std::make_shared<T>(std::move(group_description), group_name, nullptr);
            auto ptr = option_group.get();
            // move to App_p for overload resolution on older gcc versions
            App_p app_ptr = std::dynamic_pointer_cast<App>(option_group);
            add_subcommand(std::move(app_ptr));
            return ptr;
        }

        ///@}
        /// @name Subcommmands
        ///@{

        /// Add a subcommand. Inherits INHERITABLE and OptionDefaults, and help flag
        App* add_subcommand(std::string subcommand_name = "", std::string subcommand_description = "")
        {
            CLI::App_p subcom = std::shared_ptr<App>(new App(std::move(subcommand_description), subcommand_name, this));
            return add_subcommand(std::move(subcom));
        }

        /// Add a previously created app as a subcommand
        App* add_subcommand(CLI::App_p subcom)
        {
            if (!subcom)
                throw IncorrectConstruction("passed App is not valid");
            if (!subcom->name_.empty())
            {
                for (const auto& subc : subcommands_)
                    if (subc->check_name(subcom->name_) || subcom->check_name(subc->name_))
                        throw OptionAlreadyAdded(subc->name_);
            }
            subcom->parent_ = this;
            subcommands_.push_back(std::move(subcom));
            return subcommands_.back().get();
        }

        /// Removes a subcommand from the App. Takes a subcommand pointer. Returns true if found and removed.
        bool remove_subcommand(App* subcom)
        {
            // Make sure no links exist
            for (App_p& sub : subcommands_)
            {
                sub->remove_excludes(subcom);
            }

            auto iterator = std::find_if(
                std::begin(subcommands_), std::end(subcommands_), [subcom](const App_p& v) { return v.get() == subcom; });
            if (iterator != std::end(subcommands_))
            {
                subcommands_.erase(iterator);
                return true;
            }
            return false;
        }
        /// Check to see if a subcommand is part of this command (doesn't have to be in command line)
        /// returns the first subcommand if passed a nullptr
        App* get_subcommand(App* subcom) const
        {
            if (subcom == nullptr)
                throw OptionNotFound("nullptr passed");
            for (const App_p& subcomptr : subcommands_)
                if (subcomptr.get() == subcom)
                    return subcom;
            throw OptionNotFound(subcom->get_name());
        }

        /// Check to see if a subcommand is part of this command (text version)
        App* get_subcommand(std::string subcom) const
        {
            auto subc = _find_subcommand(subcom, false, false);
            if (subc == nullptr)
                throw OptionNotFound(subcom);
            return subc;
        }
        /// Get a pointer to subcommand by index
        App* get_subcommand(int index = 0) const
        {
            if (index >= 0)
            {
                auto uindex = static_cast<unsigned>(index);
                if (uindex < subcommands_.size())
                    return subcommands_[uindex].get();
            }
            throw OptionNotFound(std::to_string(index));
        }

        /// Check to see if a subcommand is part of this command and get a shared_ptr to it
        CLI::App_p get_subcommand_ptr(App* subcom) const
        {
            if (subcom == nullptr)
                throw OptionNotFound("nullptr passed");
            for (const App_p& subcomptr : subcommands_)
                if (subcomptr.get() == subcom)
                    return subcomptr;
            throw OptionNotFound(subcom->get_name());
        }

        /// Check to see if a subcommand is part of this command (text version)
        CLI::App_p get_subcommand_ptr(std::string subcom) const
        {
            for (const App_p& subcomptr : subcommands_)
                if (subcomptr->check_name(subcom))
                    return subcomptr;
            throw OptionNotFound(subcom);
        }

        /// Get an owning pointer to subcommand by index
        CLI::App_p get_subcommand_ptr(int index = 0) const
        {
            if (index >= 0)
            {
                auto uindex = static_cast<unsigned>(index);
                if (uindex < subcommands_.size())
                    return subcommands_[uindex];
            }
            throw OptionNotFound(std::to_string(index));
        }

        /// Check to see if an option group is part of this App
        App* get_option_group(std::string group_name) const
        {
            for (const App_p& app : subcommands_)
            {
                if (app->name_.empty() && app->group_ == group_name)
                {
                    return app.get();
                }
            }
            throw OptionNotFound(group_name);
        }

        /// No argument version of count counts the number of times this subcommand was
        /// passed in. The main app will return 1. Unnamed subcommands will also return 1 unless
        /// otherwise modified in a callback
        size_t count() const { return parsed_; }

        /// Get a count of all the arguments processed in options and subcommands, this excludes arguments which were
        /// treated as extras.
        size_t count_all() const
        {
            size_t cnt{ 0 };
            for (auto& opt : options_)
            {
                cnt += opt->count();
            }
            for (auto& sub : subcommands_)
            {
                cnt += sub->count_all();
            }
            if (!get_name().empty())
            { // for named subcommands add the number of times the subcommand was called
                cnt += parsed_;
            }
            return cnt;
        }

        /// Changes the group membership
        App* group(std::string group_name)
        {
            group_ = group_name;
            return this;
        }

        /// The argumentless form of require subcommand requires 1 or more subcommands
        App* require_subcommand()
        {
            require_subcommand_min_ = 1;
            require_subcommand_max_ = 0;
            return this;
        }

        /// Require a subcommand to be given (does not affect help call)
        /// The number required can be given. Negative values indicate maximum
        /// number allowed (0 for any number). Max number inheritable.
        App* require_subcommand(int value)
        {
            if (value < 0)
            {
                require_subcommand_min_ = 0;
                require_subcommand_max_ = static_cast<size_t>(-value);
            }
            else
            {
                require_subcommand_min_ = static_cast<size_t>(value);
                require_subcommand_max_ = static_cast<size_t>(value);
            }
            return this;
        }

        /// Explicitly control the number of subcommands required. Setting 0
        /// for the max means unlimited number allowed. Max number inheritable.
        App* require_subcommand(size_t min, size_t max)
        {
            require_subcommand_min_ = min;
            require_subcommand_max_ = max;
            return this;
        }

        /// The argumentless form of require option requires 1 or more options be used
        App* require_option()
        {
            require_option_min_ = 1;
            require_option_max_ = 0;
            return this;
        }

        /// Require an option to be given (does not affect help call)
        /// The number required can be given. Negative values indicate maximum
        /// number allowed (0 for any number).
        App* require_option(int value)
        {
            if (value < 0)
            {
                require_option_min_ = 0;
                require_option_max_ = static_cast<size_t>(-value);
            }
            else
            {
                require_option_min_ = static_cast<size_t>(value);
                require_option_max_ = static_cast<size_t>(value);
            }
            return this;
        }

        /// Explicitly control the number of options required. Setting 0
        /// for the max means unlimited number allowed. Max number inheritable.
        App* require_option(size_t min, size_t max)
        {
            require_option_min_ = min;
            require_option_max_ = max;
            return this;
        }

        /// Stop subcommand fallthrough, so that parent commands cannot collect commands after subcommand.
        /// Default from parent, usually set on parent.
        App* fallthrough(bool value = true)
        {
            fallthrough_ = value;
            return this;
        }

        /// Check to see if this subcommand was parsed, true only if received on command line.
        /// This allows the subcommand to be directly checked.
        operator bool() const { return parsed_ > 0; }

        ///@}
        /// @name Extras for subclassing
        ///@{

        /// This allows subclasses to inject code before callbacks but after parse.
        ///
        /// This does not run if any errors or help is thrown.
        virtual void pre_callback() {}

        ///@}
        /// @name Parsing
        ///@{
        //
        /// Reset the parsed data
        void clear()
        {
            parsed_ = 0;
            pre_parse_called_ = false;

            missing_.clear();
            parsed_subcommands_.clear();
            for (const Option_p& opt : options_)
            {
                opt->clear();
            }
            for (const App_p& subc : subcommands_)
            {
                subc->clear();
            }
        }

        /// Parses the command line - throws errors.
        /// This must be called after the options are in but before the rest of the program.
        void parse(int argc, const char* const* argv)
        {
            // If the name is not set, read from command line
            if (name_.empty() || has_automatic_name_)
            {
                has_automatic_name_ = true;
                name_ = argv[0];
            }

            std::vector<std::string> args;
            args.reserve(static_cast<size_t>(argc - 1));
            for (int i = argc - 1; i > 0; i--)
                args.emplace_back(argv[i]);
            parse(std::move(args));
        }

        /// Parse a single string as if it contained command line arguments.
        /// This function splits the string into arguments then calls parse(std::vector<std::string> &)
        /// the function takes an optional boolean argument specifying if the programName is included in the string to
        /// process
        void parse(std::string commandline, bool program_name_included = false)
        {
            if (program_name_included)
            {
                auto nstr = detail::split_program_name(commandline);
                if ((name_.empty()) || (has_automatic_name_))
                {
                    has_automatic_name_ = true;
                    name_ = nstr.first;
                }
                commandline = std::move(nstr.second);
            }
            else
                detail::trim(commandline);
            // the next section of code is to deal with quoted arguments after an '=' or ':' for windows like operations
            if (!commandline.empty())
            {
                commandline = detail::find_and_modify(commandline, "=", detail::escape_detect);
                if (allow_windows_style_options_)
                    commandline = detail::find_and_modify(commandline, ":", detail::escape_detect);
            }

            auto args = detail::split_up(std::move(commandline));
            // remove all empty strings
            args.erase(std::remove(args.begin(), args.end(), std::string{}), args.end());
            std::reverse(args.begin(), args.end());

            parse(std::move(args));
        }

        /// The real work is done here. Expects a reversed vector.
        /// Changes the vector to the remaining options.
        void parse(std::vector<std::string>& args)
        {
            // Clear if parsed
            if (parsed_ > 0)
                clear();

            // parsed_ is incremented in commands/subcommands,
            // but placed here to make sure this is cleared when
            // running parse after an error is thrown, even by _validate or _configure.
            parsed_ = 1;
            _validate();
            _configure();
            // set the parent as nullptr as this object should be the top now
            parent_ = nullptr;
            parsed_ = 0;

            _parse(args);
            run_callback();
        }

        /// The real work is done here. Expects a reversed vector.
        void parse(std::vector<std::string>&& args)
        {
            // Clear if parsed
            if (parsed_ > 0)
                clear();

            // parsed_ is incremented in commands/subcommands,
            // but placed here to make sure this is cleared when
            // running parse after an error is thrown, even by _validate or _configure.
            parsed_ = 1;
            _validate();
            _configure();
            // set the parent as nullptr as this object should be the top now
            parent_ = nullptr;
            parsed_ = 0;

            _parse(std::move(args));
            run_callback();
        }

        /// Provide a function to print a help message. The function gets access to the App pointer and error.
        void failure_message(std::function<std::string(const App*, const Error& e)> function)
        {
            failure_message_ = function;
        }

        /// Print a nice error message and return the exit code
        int exit(const Error& e, std::ostream& out = std::cout, std::ostream& err = std::cerr) const
        {
            /// Avoid printing anything if this is a CLI::RuntimeError
            if (dynamic_cast<const CLI::RuntimeError*>(&e) != nullptr)
                return e.get_exit_code();

            if (dynamic_cast<const CLI::CallForHelp*>(&e) != nullptr)
            {
                out << help();
                return e.get_exit_code();
            }

            if (dynamic_cast<const CLI::CallForAllHelp*>(&e) != nullptr)
            {
                out << help("", AppFormatMode::All);
                return e.get_exit_code();
            }

            if (e.get_exit_code() != static_cast<int>(ExitCodes::Success))
            {
                if (failure_message_)
                    err << failure_message_(this, e) << std::flush;
            }

            return e.get_exit_code();
        }

        ///@}
        /// @name Post parsing
        ///@{

        /// Counts the number of times the given option was passed.
        size_t count(std::string option_name) const { return get_option(option_name)->count(); }

        /// Get a subcommand pointer list to the currently selected subcommands (after parsing by default, in command
        /// line order; use parsed = false to get the original definition list.)
        std::vector<App*> get_subcommands() const { return parsed_subcommands_; }

        /// Get a filtered subcommand pointer list from the original definition list. An empty function will provide all
        /// subcommands (const)
        std::vector<const App*> get_subcommands(const std::function<bool(const App*)>& filter) const
        {
            std::vector<const App*> subcomms(subcommands_.size());
            std::transform(std::begin(subcommands_), std::end(subcommands_), std::begin(subcomms), [](const App_p& v) {
                return v.get();
            });

            if (filter)
            {
                subcomms.erase(std::remove_if(std::begin(subcomms),
                                              std::end(subcomms),
                                              [&filter](const App* app) { return !filter(app); }),
                               std::end(subcomms));
            }

            return subcomms;
        }

        /// Get a filtered subcommand pointer list from the original definition list. An empty function will provide all
        /// subcommands
        std::vector<App*> get_subcommands(const std::function<bool(App*)>& filter)
        {
            std::vector<App*> subcomms(subcommands_.size());
            std::transform(std::begin(subcommands_), std::end(subcommands_), std::begin(subcomms), [](const App_p& v) {
                return v.get();
            });

            if (filter)
            {
                subcomms.erase(
                    std::remove_if(std::begin(subcomms), std::end(subcomms), [&filter](App* app) { return !filter(app); }),
                    std::end(subcomms));
            }

            return subcomms;
        }

        /// Check to see if given subcommand was selected
        bool got_subcommand(App* subcom) const
        {
            // get subcom needed to verify that this was a real subcommand
            return get_subcommand(subcom)->parsed_ > 0;
        }

        /// Check with name instead of pointer to see if subcommand was selected
        bool got_subcommand(std::string subcommand_name) const { return get_subcommand(subcommand_name)->parsed_ > 0; }

        /// Sets excluded options for the subcommand
        App* excludes(Option* opt)
        {
            if (opt == nullptr)
            {
                throw OptionNotFound("nullptr passed");
            }
            exclude_options_.insert(opt);
            return this;
        }

        /// Sets excluded subcommands for the subcommand
        App* excludes(App* app)
        {
            if ((app == this) || (app == nullptr))
            {
                throw OptionNotFound("nullptr passed");
            }
            auto res = exclude_subcommands_.insert(app);
            // subcommand exclusion should be symmetric
            if (res.second)
            {
                app->exclude_subcommands_.insert(this);
            }
            return this;
        }

        /// Removes an option from the excludes list of this subcommand
        bool remove_excludes(Option* opt)
        {
            auto iterator = std::find(std::begin(exclude_options_), std::end(exclude_options_), opt);
            if (iterator != std::end(exclude_options_))
            {
                exclude_options_.erase(iterator);
                return true;
            }
            else
            {
                return false;
            }
        }

        /// Removes a subcommand from this excludes list of this subcommand
        bool remove_excludes(App* app)
        {
            auto iterator = std::find(std::begin(exclude_subcommands_), std::end(exclude_subcommands_), app);
            if (iterator != std::end(exclude_subcommands_))
            {
                auto other_app = *iterator;
                exclude_subcommands_.erase(iterator);
                other_app->remove_excludes(this);
                return true;
            }
            else
            {
                return false;
            }
        }

        ///@}
        /// @name Help
        ///@{

        /// Set footer.
        App* footer(std::string footer_string)
        {
            footer_ = std::move(footer_string);
            return this;
        }

        /// Produce a string that could be read in as a config of the current values of the App. Set default_also to
        /// include default arguments. Prefix will add a string to the beginning of each option.
        std::string config_to_str(bool default_also = false, bool write_description = false) const
        {
            return config_formatter_->to_config(this, default_also, write_description, "");
        }

        /// Makes a help message, using the currently configured formatter
        /// Will only do one subcommand at a time
        std::string help(std::string prev = "", AppFormatMode mode = AppFormatMode::Normal) const
        {
            if (prev.empty())
                prev = get_name();
            else
                prev += " " + get_name();

            // Delegate to subcommand if needed
            auto selected_subcommands = get_subcommands();
            if (!selected_subcommands.empty())
                return selected_subcommands.at(0)->help(prev, mode);
            else
                return formatter_->make_help(this, prev, mode);
        }

        ///@}
        /// @name Getters
        ///@{

        /// Access the formatter
        std::shared_ptr<FormatterBase> get_formatter() const { return formatter_; }

        /// Access the config formatter
        std::shared_ptr<Config> get_config_formatter() const { return config_formatter_; }

        /// Get the app or subcommand description
        std::string get_description() const { return description_; }

        /// Set the description of the app
        App* description(std::string app_description)
        {
            description_ = std::move(app_description);
            return this;
        }

        /// Get the list of options (user facing function, so returns raw pointers), has optional filter function
        std::vector<const Option*> get_options(const std::function<bool(const Option*)> filter = {}) const
        {
            std::vector<const Option*> options(options_.size());
            std::transform(std::begin(options_), std::end(options_), std::begin(options), [](const Option_p& val) {
                return val.get();
            });

            if (filter)
            {
                options.erase(std::remove_if(std::begin(options),
                                             std::end(options),
                                             [&filter](const Option* opt) { return !filter(opt); }),
                              std::end(options));
            }

            return options;
        }

        /// Get an option by name (noexcept non-const version)
        Option* get_option_no_throw(std::string option_name) noexcept
        {
            for (Option_p& opt : options_)
            {
                if (opt->check_name(option_name))
                {
                    return opt.get();
                }
            }
            for (auto& subc : subcommands_)
            {
                // also check down into nameless subcommands
                if (subc->get_name().empty())
                {
                    auto opt = subc->get_option_no_throw(option_name);
                    if (opt != nullptr)
                    {
                        return opt;
                    }
                }
            }
            return nullptr;
        }

        /// Get an option by name (noexcept const version)
        const Option* get_option_no_throw(std::string option_name) const noexcept
        {
            for (const Option_p& opt : options_)
            {
                if (opt->check_name(option_name))
                {
                    return opt.get();
                }
            }
            for (const auto& subc : subcommands_)
            {
                // also check down into nameless subcommands
                if (subc->get_name().empty())
                {
                    auto opt = subc->get_option_no_throw(option_name);
                    if (opt != nullptr)
                    {
                        return opt;
                    }
                }
            }
            return nullptr;
        }

        /// Get an option by name
        const Option* get_option(std::string option_name) const
        {
            auto opt = get_option_no_throw(option_name);
            if (opt == nullptr)
            {
                throw OptionNotFound(option_name);
            }
            return opt;
        }

        /// Get an option by name (non-const version)
        Option* get_option(std::string option_name)
        {
            auto opt = get_option_no_throw(option_name);
            if (opt == nullptr)
            {
                throw OptionNotFound(option_name);
            }
            return opt;
        }

        /// Shortcut bracket operator for getting a pointer to an option
        const Option* operator[](const std::string& option_name) const { return get_option(option_name); }

        /// Shortcut bracket operator for getting a pointer to an option
        const Option* operator[](const char* option_name) const { return get_option(option_name); }

        /// Check the status of ignore_case
        bool get_ignore_case() const { return ignore_case_; }

        /// Check the status of ignore_underscore
        bool get_ignore_underscore() const { return ignore_underscore_; }

        /// Check the status of fallthrough
        bool get_fallthrough() const { return fallthrough_; }

        /// Check the status of the allow windows style options
        bool get_allow_windows_style_options() const { return allow_windows_style_options_; }

        /// Check the status of the allow windows style options
        bool get_positionals_at_end() const { return positionals_at_end_; }

        /// Get the group of this subcommand
        const std::string& get_group() const { return group_; }

        /// Get footer.
        const std::string& get_footer() const { return footer_; }

        /// Get the required min subcommand value
        size_t get_require_subcommand_min() const { return require_subcommand_min_; }

        /// Get the required max subcommand value
        size_t get_require_subcommand_max() const { return require_subcommand_max_; }

        /// Get the required min option value
        size_t get_require_option_min() const { return require_option_min_; }

        /// Get the required max option value
        size_t get_require_option_max() const { return require_option_max_; }

        /// Get the prefix command status
        bool get_prefix_command() const { return prefix_command_; }

        /// Get the status of allow extras
        bool get_allow_extras() const { return allow_extras_; }

        /// Get the status of required
        bool get_required() const { return required_; }

        /// Get the status of disabled
        bool get_disabled() const { return disabled_; }

        /// Get the status of disabled
        bool get_immediate_callback() const { return immediate_callback_; }

        /// Get the status of disabled by default
        bool get_disabled_by_default() const { return disabled_by_default_; }

        /// Get the status of disabled by default
        bool get_enabled_by_default() const { return enabled_by_default_; }
        /// Get the status of validating positionals
        bool get_validate_positionals() const { return validate_positionals_; }

        /// Get the status of allow extras
        bool get_allow_config_extras() const { return allow_config_extras_; }

        /// Get a pointer to the help flag.
        Option* get_help_ptr() { return help_ptr_; }

        /// Get a pointer to the help flag. (const)
        const Option* get_help_ptr() const { return help_ptr_; }

        /// Get a pointer to the help all flag. (const)
        const Option* get_help_all_ptr() const { return help_all_ptr_; }

        /// Get a pointer to the config option.
        Option* get_config_ptr() { return config_ptr_; }

        /// Get a pointer to the config option. (const)
        const Option* get_config_ptr() const { return config_ptr_; }

        /// Get the parent of this subcommand (or nullptr if master app)
        App* get_parent() { return parent_; }

        /// Get the parent of this subcommand (or nullptr if master app) (const version)
        const App* get_parent() const { return parent_; }

        /// Get the name of the current app
        std::string get_name() const { return name_; }

        /// Get a display name for an app
        std::string get_display_name() const { return (!name_.empty()) ? name_ : "[Option Group: " + get_group() + "]"; }

        /// Check the name, case insensitive and underscore insensitive if set
        bool check_name(std::string name_to_check) const
        {
            std::string local_name = name_;
            if (ignore_underscore_)
            {
                local_name = detail::remove_underscore(name_);
                name_to_check = detail::remove_underscore(name_to_check);
            }
            if (ignore_case_)
            {
                local_name = detail::to_lower(name_);
                name_to_check = detail::to_lower(name_to_check);
            }

            return local_name == name_to_check;
        }

        /// Get the groups available directly from this option (in order)
        std::vector<std::string> get_groups() const
        {
            std::vector<std::string> groups;

            for (const Option_p& opt : options_)
            {
                // Add group if it is not already in there
                if (std::find(groups.begin(), groups.end(), opt->get_group()) == groups.end())
                {
                    groups.push_back(opt->get_group());
                }
            }

            return groups;
        }

        /// This gets a vector of pointers with the original parse order
        const std::vector<Option*>& parse_order() const { return parse_order_; }

        /// This returns the missing options from the current subcommand
        std::vector<std::string> remaining(bool recurse = false) const
        {
            std::vector<std::string> miss_list;
            for (const std::pair<detail::Classifier, std::string>& miss : missing_)
            {
                miss_list.push_back(std::get<1>(miss));
            }
            // Get from a subcommand that may allow extras
            if (recurse)
            {
                if (!allow_extras_)
                {
                    for (const auto& sub : subcommands_)
                    {
                        if (sub->name_.empty() && !sub->missing_.empty())
                        {
                            for (const std::pair<detail::Classifier, std::string>& miss : sub->missing_)
                            {
                                miss_list.push_back(std::get<1>(miss));
                            }
                        }
                    }
                }
                // Recurse into subcommands

                for (const App* sub : parsed_subcommands_)
                {
                    std::vector<std::string> output = sub->remaining(recurse);
                    std::copy(std::begin(output), std::end(output), std::back_inserter(miss_list));
                }
            }
            return miss_list;
        }

        /// This returns the missing options in a form ready for processing by another command line program
        std::vector<std::string> remaining_for_passthrough(bool recurse = false) const
        {
            std::vector<std::string> miss_list = remaining(recurse);
            std::reverse(std::begin(miss_list), std::end(miss_list));
            return miss_list;
        }

        /// This returns the number of remaining options, minus the -- separator
        size_t remaining_size(bool recurse = false) const
        {
            auto remaining_options = static_cast<size_t>(std::count_if(
                std::begin(missing_), std::end(missing_), [](const std::pair<detail::Classifier, std::string>& val) {
                    return val.first != detail::Classifier::POSITIONAL_MARK;
                }));

            if (recurse)
            {
                for (const App_p& sub : subcommands_)
                {
                    remaining_options += sub->remaining_size(recurse);
                }
            }
            return remaining_options;
        }

        ///@}

    protected:
        /// Check the options to make sure there are no conflicts.
        ///
        /// Currently checks to see if multiple positionals exist with -1 args and checks if the min and max options are
        /// feasible
        void _validate() const
        {
            auto pcount = std::count_if(std::begin(options_), std::end(options_), [](const Option_p& opt) {
                return opt->get_items_expected() < 0 && opt->get_positional();
            });
            if (pcount > 1)
                throw InvalidError(name_);

            size_t nameless_subs{ 0 };
            for (const App_p& app : subcommands_)
            {
                app->_validate();
                if (app->get_name().empty())
                    ++nameless_subs;
            }

            if (require_option_min_ > 0)
            {
                if (require_option_max_ > 0)
                {
                    if (require_option_max_ < require_option_min_)
                    {
                        throw(InvalidError("Required min options greater than required max options",
                                           ExitCodes::InvalidError));
                    }
                }
                if (require_option_min_ > (options_.size() + nameless_subs))
                {
                    throw(InvalidError("Required min options greater than number of available options",
                                       ExitCodes::InvalidError));
                }
            }
        }

        /// configure subcommands to enable parsing through the current object
        /// set the correct fallthrough and prefix for nameless subcommands and manage the automatic enable or disable
        /// makes sure parent is set correctly
        void _configure()
        {
            if (disabled_by_default_)
            {
                disabled_ = true;
            }
            if (enabled_by_default_)
            {
                disabled_ = false;
            }
            for (const App_p& app : subcommands_)
            {
                if (app->has_automatic_name_)
                {
                    app->name_.clear();
                }
                if (app->name_.empty())
                {
                    app->fallthrough_ = false; // make sure fallthrough_ is false to prevent infinite loop
                    app->prefix_command_ = false;
                }
                // make sure the parent is set to be this object in preparation for parse
                app->parent_ = this;
                app->_configure();
            }
        }
        /// Internal function to run (App) callback, bottom up
        void run_callback()
        {
            pre_callback();
            // run the callbacks for the received subcommands
            for (App* subc : get_subcommands())
            {
                if (!subc->immediate_callback_)
                    subc->run_callback();
            }
            // now run callbacks for option_groups
            for (auto& subc : subcommands_)
            {
                if (!subc->immediate_callback_ && subc->name_.empty() && subc->count_all() > 0)
                {
                    subc->run_callback();
                }
            }
            // finally run the main callback
            if (callback_ && (parsed_ > 0))
            {
                if (!name_.empty() || count_all() > 0)
                {
                    callback_();
                }
            }
        }

        /// Check to see if a subcommand is valid. Give up immediately if subcommand max has been reached.
        bool _valid_subcommand(const std::string& current, bool ignore_used = true) const
        {
            // Don't match if max has been reached - but still check parents
            if (require_subcommand_max_ != 0 && parsed_subcommands_.size() >= require_subcommand_max_)
            {
                return parent_ != nullptr && parent_->_valid_subcommand(current, ignore_used);
            }
            auto com = _find_subcommand(current, true, ignore_used);
            if (com != nullptr)
            {
                return true;
            }
            // Check parent if exists, else return false
            return parent_ != nullptr && parent_->_valid_subcommand(current, ignore_used);
        }

        /// Selects a Classifier enum based on the type of the current argument
        detail::Classifier _recognize(const std::string& current, bool ignore_used_subcommands = true) const
        {
            std::string dummy1, dummy2;

            if (current == "--")
                return detail::Classifier::POSITIONAL_MARK;
            if (_valid_subcommand(current, ignore_used_subcommands))
                return detail::Classifier::SUBCOMMAND;
            if (detail::split_long(current, dummy1, dummy2))
                return detail::Classifier::LONG;
            if (detail::split_short(current, dummy1, dummy2))
                return detail::Classifier::SHORT;
            if ((allow_windows_style_options_) && (detail::split_windows_style(current, dummy1, dummy2)))
                return detail::Classifier::WINDOWS;
            if ((current == "++") && !name_.empty() && parent_ != nullptr)
                return detail::Classifier::SUBCOMMAND_TERMINATOR;
            return detail::Classifier::NONE;
        }

        // The parse function is now broken into several parts, and part of process

        /// Read and process an ini file (main app only)
        void _process_ini()
        {
            // Process an INI file
            if (config_ptr_ != nullptr)
            {
                if (*config_ptr_)
                {
                    config_ptr_->run_callback();
                    config_required_ = true;
                }
                if (!config_name_.empty())
                {
                    try
                    {
                        std::vector<ConfigItem> values = config_formatter_->from_file(config_name_);
                        _parse_config(values);
                    }
                    catch (const FileError&)
                    {
                        if (config_required_)
                            throw;
                    }
                }
            }
        }

        /// Get envname options if not yet passed. Runs on *all* subcommands.
        void _process_env()
        {
            for (const Option_p& opt : options_)
            {
                if (opt->count() == 0 && !opt->envname_.empty())
                {
                    char* buffer = nullptr;
                    std::string ename_string;

#ifdef _MSC_VER
                    // Windows version
                    size_t sz = 0;
                    if (_dupenv_s(&buffer, &sz, opt->envname_.c_str()) == 0 && buffer != nullptr)
                    {
                        ename_string = std::string(buffer);
                        free(buffer);
                    }
#else
                    // This also works on Windows, but gives a warning
                    buffer = std::getenv(opt->envname_.c_str());
                    if (buffer != nullptr)
                        ename_string = std::string(buffer);
#endif

                    if (!ename_string.empty())
                    {
                        opt->add_result(ename_string);
                    }
                }
            }

            for (App_p& sub : subcommands_)
            {
                if (sub->get_name().empty() || !sub->immediate_callback_)
                    sub->_process_env();
            }
        }

        /// Process callbacks. Runs on *all* subcommands.
        void _process_callbacks()
        {
            for (App_p& sub : subcommands_)
            {
                // process the priority option_groups first
                if (sub->get_name().empty() && sub->immediate_callback_)
                {
                    if (sub->count_all() > 0)
                    {
                        sub->_process_callbacks();
                        sub->run_callback();
                    }
                }
            }

            for (const Option_p& opt : options_)
            {
                if (opt->count() > 0 && !opt->get_callback_run())
                {
                    opt->run_callback();
                }
            }

            for (App_p& sub : subcommands_)
            {
                if (!sub->immediate_callback_)
                {
                    sub->_process_callbacks();
                }
            }
        }

        /// Run help flag processing if any are found.
        ///
        /// The flags allow recursive calls to remember if there was a help flag on a parent.
        void _process_help_flags(bool trigger_help = false, bool trigger_all_help = false) const
        {
            const Option* help_ptr = get_help_ptr();
            const Option* help_all_ptr = get_help_all_ptr();

            if (help_ptr != nullptr && help_ptr->count() > 0)
                trigger_help = true;
            if (help_all_ptr != nullptr && help_all_ptr->count() > 0)
                trigger_all_help = true;

            // If there were parsed subcommands, call those. First subcommand wins if there are multiple ones.
            if (!parsed_subcommands_.empty())
            {
                for (const App* sub : parsed_subcommands_)
                    sub->_process_help_flags(trigger_help, trigger_all_help);

                // Only the final subcommand should call for help. All help wins over help.
            }
            else if (trigger_all_help)
            {
                throw CallForAllHelp();
            }
            else if (trigger_help)
            {
                throw CallForHelp();
            }
        }

        /// Verify required options and cross requirements. Subcommands too (only if selected).
        void _process_requirements()
        {
            // check excludes
            bool excluded{ false };
            std::string excluder;
            for (auto& opt : exclude_options_)
            {
                if (opt->count() > 0)
                {
                    excluded = true;
                    excluder = opt->get_name();
                }
            }
            for (auto& subc : exclude_subcommands_)
            {
                if (subc->count_all() > 0)
                {
                    excluded = true;
                    excluder = subc->get_display_name();
                }
            }
            if (excluded)
            {
                if (count_all() > 0)
                {
                    throw ExcludesError(get_display_name(), excluder);
                }
                // if we are excluded but didn't receive anything, just return
                return;
            }
            size_t used_options = 0;
            for (const Option_p& opt : options_)
            {
                if (opt->count() != 0)
                {
                    ++used_options;
                }
                // Required or partially filled
                if (opt->get_required() || opt->count() != 0)
                {
                    // Make sure enough -N arguments parsed (+N is already handled in parsing function)
                    if (opt->get_items_expected() < 0 && opt->count() < static_cast<size_t>(-opt->get_items_expected()))
                        throw ArgumentMismatch::AtLeast(opt->get_name(), -opt->get_items_expected());

                    // Required but empty
                    if (opt->get_required() && opt->count() == 0)
                        throw RequiredError(opt->get_name());
                }
                // Requires
                for (const Option* opt_req : opt->needs_)
                    if (opt->count() > 0 && opt_req->count() == 0)
                        throw RequiresError(opt->get_name(), opt_req->get_name());
                // Excludes
                for (const Option* opt_ex : opt->excludes_)
                    if (opt->count() > 0 && opt_ex->count() != 0)
                        throw ExcludesError(opt->get_name(), opt_ex->get_name());
            }
            // check for the required number of subcommands
            if (require_subcommand_min_ > 0)
            {
                auto selected_subcommands = get_subcommands();
                if (require_subcommand_min_ > selected_subcommands.size())
                    throw RequiredError::Subcommand(require_subcommand_min_);
            }

            // Max error cannot occur, the extra subcommand will parse as an ExtrasError or a remaining item.

            // run this loop to check how many unnamed subcommands were actually used since they are considered options from
            // the perspective of an App
            for (App_p& sub : subcommands_)
            {
                if (sub->disabled_)
                    continue;
                if (sub->name_.empty() && sub->count_all() > 0)
                {
                    ++used_options;
                }
            }

            if (require_option_min_ > used_options || (require_option_max_ > 0 && require_option_max_ < used_options))
            {
                auto option_list = detail::join(options_, [](const Option_p& ptr) { return ptr->get_name(false, true); });
                if (option_list.compare(0, 10, "-h,--help,") == 0)
                {
                    option_list.erase(0, 10);
                }
                auto subc_list = get_subcommands([](App* app) { return ((app->get_name().empty()) && (!app->disabled_)); });
                if (!subc_list.empty())
                {
                    option_list += "," + detail::join(subc_list, [](const App* app) { return app->get_display_name(); });
                }
                throw RequiredError::Option(require_option_min_, require_option_max_, used_options, option_list);
            }

            // now process the requirements for subcommands if needed
            for (App_p& sub : subcommands_)
            {
                if (sub->disabled_)
                    continue;
                if (sub->name_.empty() && sub->required_ == false)
                {
                    if (sub->count_all() == 0)
                    {
                        if (require_option_min_ > 0 && require_option_min_ <= used_options)
                        {
                            continue;
                            // if we have met the requirement and there is nothing in this option group skip checking
                            // requirements
                        }
                        if (require_option_max_ > 0 && used_options >= require_option_min_)
                        {
                            continue;
                            // if we have met the requirement and there is nothing in this option group skip checking
                            // requirements
                        }
                    }
                }
                if (sub->count() > 0 || sub->name_.empty())
                {
                    sub->_process_requirements();
                }

                if (sub->required_ && sub->count_all() == 0)
                {
                    throw(CLI::RequiredError(sub->get_display_name()));
                }
            }
        }

        /// Process callbacks and such.
        void _process()
        {
            _process_ini();
            _process_env();
            _process_callbacks();
            _process_help_flags();
            _process_requirements();
        }

        /// Throw an error if anything is left over and should not be.
        void _process_extras()
        {
            if (!(allow_extras_ || prefix_command_))
            {
                size_t num_left_over = remaining_size();
                if (num_left_over > 0)
                {
                    throw ExtrasError(remaining(false));
                }
            }

            for (App_p& sub : subcommands_)
            {
                if (sub->count() > 0)
                    sub->_process_extras();
            }
        }

        /// Throw an error if anything is left over and should not be.
        /// Modifies the args to fill in the missing items before throwing.
        void _process_extras(std::vector<std::string>& args)
        {
            if (!(allow_extras_ || prefix_command_))
            {
                size_t num_left_over = remaining_size();
                if (num_left_over > 0)
                {
                    args = remaining(false);
                    throw ExtrasError(args);
                }
            }

            for (App_p& sub : subcommands_)
            {
                if (sub->count() > 0)
                    sub->_process_extras(args);
            }
        }

        /// Internal function to recursively increment the parsed counter on the current app as well unnamed subcommands
        void increment_parsed()
        {
            ++parsed_;
            for (App_p& sub : subcommands_)
            {
                if (sub->get_name().empty())
                    sub->increment_parsed();
            }
        }
        /// Internal parse function
        void _parse(std::vector<std::string>& args)
        {
            increment_parsed();
            _trigger_pre_parse(args.size());
            bool positional_only = false;

            while (!args.empty())
            {
                if (!_parse_single(args, positional_only))
                {
                    break;
                }
            }

            if (parent_ == nullptr)
            {
                _process();

                // Throw error if any items are left over (depending on settings)
                _process_extras(args);

                // Convert missing (pairs) to extras (string only) ready for processing in another app
                args = remaining_for_passthrough(false);
            }
            else if (immediate_callback_)
            {
                _process_env();
                _process_callbacks();
                _process_help_flags();
                _process_requirements();
                run_callback();
            }
        }

        /// Internal parse function
        void _parse(std::vector<std::string>&& args)
        {
            // this can only be called by the top level in which case parent == nullptr by definition
            // operation is simplified
            increment_parsed();
            _trigger_pre_parse(args.size());
            bool positional_only = false;

            while (!args.empty())
            {
                _parse_single(args, positional_only);
            }
            _process();

            // Throw error if any items are left over (depending on settings)
            _process_extras();
        }

        /// Parse one config param, return false if not found in any subcommand, remove if it is
        ///
        /// If this has more than one dot.separated.name, go into the subcommand matching it
        /// Returns true if it managed to find the option, if false you'll need to remove the arg manually.
        void _parse_config(std::vector<ConfigItem>& args)
        {
            for (ConfigItem item : args)
            {
                if (!_parse_single_config(item) && !allow_config_extras_)
                    throw ConfigError::Extras(item.fullname());
            }
        }

        /// Fill in a single config option
        bool _parse_single_config(const ConfigItem& item, size_t level = 0)
        {
            if (level < item.parents.size())
            {
                try
                {
                    auto subcom = get_subcommand(item.parents.at(level));
                    return subcom->_parse_single_config(item, level + 1);
                }
                catch (const OptionNotFound&)
                {
                    return false;
                }
            }

            Option* op = get_option_no_throw("--" + item.name);
            if (op == nullptr)
            {
                // If the option was not present
                if (get_allow_config_extras())
                    // Should we worry about classifying the extras properly?
                    missing_.emplace_back(detail::Classifier::NONE, item.fullname());
                return false;
            }

            if (!op->get_configurable())
                throw ConfigError::NotConfigurable(item.fullname());

            if (op->empty())
            {
                // Flag parsing
                if (op->get_type_size() == 0)
                {
                    auto res = config_formatter_->to_flag(item);
                    res = op->get_flag_value(item.name, res);

                    op->add_result(res);
                }
                else
                {
                    op->add_result(item.inputs);
                    op->run_callback();
                }
            }

            return true;
        }

        /// Parse "one" argument (some may eat more than one), delegate to parent if fails, add to missing if missing
        /// from master return false if the parse has failed and needs to return to parent
        bool _parse_single(std::vector<std::string>& args, bool& positional_only)
        {
            bool retval = true;
            detail::Classifier classifier = positional_only ? detail::Classifier::NONE : _recognize(args.back());
            switch (classifier)
            {
            case detail::Classifier::POSITIONAL_MARK:
                args.pop_back();
                positional_only = true;
                if ((!_has_remaining_positionals()) && (parent_ != nullptr))
                {
                    retval = false;
                }
                else
                {
                    _move_to_missing(classifier, "--");
                }
                break;
            case detail::Classifier::SUBCOMMAND_TERMINATOR:
                // treat this like a positional mark if in the parent app
                args.pop_back();
                retval = false;
                break;
            case detail::Classifier::SUBCOMMAND:
                retval = _parse_subcommand(args);
                break;
            case detail::Classifier::LONG:
            case detail::Classifier::SHORT:
            case detail::Classifier::WINDOWS:
                // If already parsed a subcommand, don't accept options_
                _parse_arg(args, classifier);
                break;
            case detail::Classifier::NONE:
                // Probably a positional or something for a parent (sub)command
                retval = _parse_positional(args);
                if (retval && positionals_at_end_)
                {
                    positional_only = true;
                }
                break;

                // LCOV_EXCL_START
            default:
                HorribleError("unrecognized classifier (you should not see this!)");
                // LCOV_EXCL_END
            }
            return retval;
        }

        /// Count the required remaining positional arguments
        size_t _count_remaining_positionals(bool required_only = false) const
        {
            size_t retval = 0;
            for (const Option_p& opt : options_)
                if (opt->get_positional() && (!required_only || opt->get_required()) && opt->get_items_expected() > 0 &&
                    static_cast<int>(opt->count()) < opt->get_items_expected())
                    retval = static_cast<size_t>(opt->get_items_expected()) - opt->count();

            return retval;
        }

        /// Count the required remaining positional arguments
        bool _has_remaining_positionals() const
        {
            for (const Option_p& opt : options_)
                if (opt->get_positional() &&
                    ((opt->get_items_expected() < 0) || ((static_cast<int>(opt->count()) < opt->get_items_expected()))))
                    return true;

            return false;
        }

        /// Parse a positional, go up the tree to check
        /// Return true if the positional was used false otherwise
        bool _parse_positional(std::vector<std::string>& args)
        {
            const std::string& positional = args.back();
            for (const Option_p& opt : options_)
            {
                // Eat options, one by one, until done
                if (opt->get_positional() &&
                    (static_cast<int>(opt->count()) < opt->get_items_expected() || opt->get_items_expected() < 0))
                {
                    if (validate_positionals_)
                    {
                        std::string pos = positional;
                        pos = opt->_validate(pos);
                        if (!pos.empty())
                        {
                            continue;
                        }
                    }
                    opt->add_result(positional);
                    parse_order_.push_back(opt.get());
                    args.pop_back();
                    return true;
                }
            }

            for (auto& subc : subcommands_)
            {
                if ((subc->name_.empty()) && (!subc->disabled_))
                {
                    if (subc->_parse_positional(args))
                    {
                        if (!subc->pre_parse_called_)
                        {
                            subc->_trigger_pre_parse(args.size());
                        }
                        return true;
                    }
                }
            }
            // let the parent deal with it if possible
            if (parent_ != nullptr && fallthrough_)
                return _get_fallthrough_parent()->_parse_positional(args);

            /// Try to find a local subcommand that is repeated
            auto com = _find_subcommand(args.back(), true, false);
            if (com != nullptr && (require_subcommand_max_ == 0 || require_subcommand_max_ > parsed_subcommands_.size()))
            {
                args.pop_back();
                com->_parse(args);
                return true;
            }
            /// now try one last gasp at subcommands that have been executed before, go to root app and try to find a
            /// subcommand in a broader way, if one exists let the parent deal with it
            auto parent_app = (parent_ != nullptr) ? _get_fallthrough_parent() : this;
            com = parent_app->_find_subcommand(args.back(), true, false);
            if (com != nullptr && (com->parent_->require_subcommand_max_ == 0 ||
                                   com->parent_->require_subcommand_max_ > com->parent_->parsed_subcommands_.size()))
            {
                return false;
            }

            if (positionals_at_end_)
            {
                throw CLI::ExtrasError(args);
            }
            /// If this is an option group don't deal with it
            if (parent_ != nullptr && name_.empty())
            {
                return false;
            }
            /// We are out of other options this goes to missing
            _move_to_missing(detail::Classifier::NONE, positional);
            args.pop_back();
            if (prefix_command_)
            {
                while (!args.empty())
                {
                    _move_to_missing(detail::Classifier::NONE, args.back());
                    args.pop_back();
                }
            }

            return true;
        }

        /// Locate a subcommand by name with two conditions, should disabled subcommands be ignored, and should used
        /// subcommands be ignored
        App* _find_subcommand(const std::string& subc_name, bool ignore_disabled, bool ignore_used) const noexcept
        {
            for (const App_p& com : subcommands_)
            {
                if (com->disabled_ && ignore_disabled)
                    continue;
                if (com->get_name().empty())
                {
                    auto subc = com->_find_subcommand(subc_name, ignore_disabled, ignore_used);
                    if (subc != nullptr)
                    {
                        return subc;
                    }
                }
                else if (com->check_name(subc_name))
                {
                    if ((!*com) || !ignore_used)
                        return com.get();
                }
            }
            return nullptr;
        }

        /// Parse a subcommand, modify args and continue
        ///
        /// Unlike the others, this one will always allow fallthrough
        /// return true if the subcommand was processed false otherwise
        bool _parse_subcommand(std::vector<std::string>& args)
        {
            if (_count_remaining_positionals(/* required */ true) > 0)
            {
                _parse_positional(args);
                return true;
            }
            auto com = _find_subcommand(args.back(), true, true);
            if (com != nullptr)
            {
                args.pop_back();
                parsed_subcommands_.push_back(com);
                com->_parse(args);
                auto parent_app = com->parent_;
                while (parent_app != this)
                {
                    parent_app->_trigger_pre_parse(args.size());
                    parent_app->parsed_subcommands_.push_back(com);
                    parent_app = parent_app->parent_;
                }
                return true;
            }

            if (parent_ == nullptr)
                throw HorribleError("Subcommand " + args.back() + " missing");
            return false;
        }

        /// Parse a short (false) or long (true) argument, must be at the top of the list
        /// return true if the argument was processed or false if nothing was done
        bool _parse_arg(std::vector<std::string>& args, detail::Classifier current_type)
        {
            std::string current = args.back();

            std::string arg_name;
            std::string value;
            std::string rest;

            switch (current_type)
            {
            case detail::Classifier::LONG:
                if (!detail::split_long(current, arg_name, value))
                    throw HorribleError("Long parsed but missing (you should not see this):" + args.back());
                break;
            case detail::Classifier::SHORT:
                if (!detail::split_short(current, arg_name, rest))
                    throw HorribleError("Short parsed but missing! You should not see this");
                break;
            case detail::Classifier::WINDOWS:
                if (!detail::split_windows_style(current, arg_name, value))
                    throw HorribleError("windows option parsed but missing! You should not see this");
                break;
            case detail::Classifier::SUBCOMMAND:
            case detail::Classifier::POSITIONAL_MARK:
            case detail::Classifier::NONE:
            default:
                throw HorribleError("parsing got called with invalid option! You should not see this");
            }

            auto op_ptr =
                std::find_if(std::begin(options_), std::end(options_), [arg_name, current_type](const Option_p& opt) {
                    if (current_type == detail::Classifier::LONG)
                        return opt->check_lname(arg_name);
                    if (current_type == detail::Classifier::SHORT)
                        return opt->check_sname(arg_name);
                    // this will only get called for detail::Classifier::WINDOWS
                    return opt->check_lname(arg_name) || opt->check_sname(arg_name);
                });

            // Option not found
            if (op_ptr == std::end(options_))
            {
                for (auto& subc : subcommands_)
                {
                    if (subc->name_.empty() && !subc->disabled_)
                    {
                        if (subc->_parse_arg(args, current_type))
                        {
                            if (!subc->pre_parse_called_)
                            {
                                subc->_trigger_pre_parse(args.size());
                            }
                            return true;
                        }
                    }
                }
                // If a subcommand, try the master command
                if (parent_ != nullptr && fallthrough_)
                    return _get_fallthrough_parent()->_parse_arg(args, current_type);
                // don't capture missing if this is a nameless subcommand
                if (parent_ != nullptr && name_.empty())
                {
                    return false;
                }
                // Otherwise, add to missing
                args.pop_back();
                _move_to_missing(current_type, current);
                return true;
            }

            args.pop_back();

            // Get a reference to the pointer to make syntax bearable
            Option_p& op = *op_ptr;

            int num = op->get_items_expected();

            // Make sure we always eat the minimum for unlimited vectors
            int collected = 0;
            int result_count = 0;
            // deal with flag like things
            if (num == 0)
            {
                auto res = op->get_flag_value(arg_name, value);
                op->add_result(res);
                parse_order_.push_back(op.get());
            }
            // --this=value
            else if (!value.empty())
            {
                op->add_result(value, result_count);
                parse_order_.push_back(op.get());
                collected += result_count;
                // If exact number expected
                if (num > 0)
                    num = (num >= result_count) ? num - result_count : 0;

                // -Trest
            }
            else if (!rest.empty())
            {
                op->add_result(rest, result_count);
                parse_order_.push_back(op.get());
                rest = "";
                collected += result_count;
                // If exact number expected
                if (num > 0)
                    num = (num >= result_count) ? num - result_count : 0;
            }

            // Unlimited vector parser
            if (num < 0)
            {
                while (!args.empty() && _recognize(args.back(), false) == detail::Classifier::NONE)
                {
                    if (collected >= -num)
                    {
                        // We could break here for allow extras, but we don't

                        // If any positionals remain, don't keep eating
                        if (_count_remaining_positionals() > 0)
                            break;
                    }
                    op->add_result(args.back(), result_count);
                    parse_order_.push_back(op.get());
                    args.pop_back();
                    collected += result_count;
                }

                // Allow -- to end an unlimited list and "eat" it
                if (!args.empty() && _recognize(args.back()) == detail::Classifier::POSITIONAL_MARK)
                    args.pop_back();
            }
            else
            {
                while (num > 0 && !args.empty())
                {
                    std::string current_ = args.back();
                    args.pop_back();
                    op->add_result(current_, result_count);
                    parse_order_.push_back(op.get());
                    num -= result_count;
                }

                if (num > 0)
                {
                    throw ArgumentMismatch::TypedAtLeast(op->get_name(), num, op->get_type_name());
                }
            }

            if (!rest.empty())
            {
                rest = "-" + rest;
                args.push_back(rest);
            }
            return true;
        }

        /// Trigger the pre_parse callback if needed
        void _trigger_pre_parse(size_t remaining_args)
        {
            if (!pre_parse_called_)
            {
                pre_parse_called_ = true;
                if (pre_parse_callback_)
                {
                    pre_parse_callback_(remaining_args);
                }
            }
            else if (immediate_callback_)
            {
                if (!name_.empty())
                {
                    auto pcnt = parsed_;
                    auto extras = std::move(missing_);
                    clear();
                    parsed_ = pcnt;
                    pre_parse_called_ = true;
                    missing_ = std::move(extras);
                }
            }
        }

        /// Get the appropriate parent to fallthrough to which is the first one that has a name or the main app
        App* _get_fallthrough_parent()
        {
            if (parent_ == nullptr)
            {
                throw(HorribleError("No Valid parent"));
            }
            auto fallthrough_parent = parent_;
            while ((fallthrough_parent->parent_ != nullptr) && (fallthrough_parent->get_name().empty()))
            {
                fallthrough_parent = fallthrough_parent->parent_;
            }
            return fallthrough_parent;
        }

        /// Helper function to place extra values in the most appropriate position
        void _move_to_missing(detail::Classifier val_type, const std::string& val)
        {
            if (allow_extras_ || subcommands_.empty())
            {
                missing_.emplace_back(val_type, val);
                return;
            }
            // allow extra arguments to be places in an option group if it is allowed there
            for (auto& subc : subcommands_)
            {
                if (subc->name_.empty() && subc->allow_extras_)
                {
                    subc->missing_.emplace_back(val_type, val);
                    return;
                }
            }
            // if we haven't found any place to put them yet put them in missing
            missing_.emplace_back(val_type, val);
        }

    public:
        /// function that could be used by subclasses of App to shift options around into subcommands
        void _move_option(Option* opt, App* app)
        {
            if (opt == nullptr)
            {
                throw OptionNotFound("the option is NULL");
            }
            // verify that the give app is actually a subcommand
            bool found = false;
            for (auto& subc : subcommands_)
            {
                if (app == subc.get())
                {
                    found = true;
                }
            }
            if (!found)
            {
                throw OptionNotFound("The Given app is not a subcommand");
            }

            if ((help_ptr_ == opt) || (help_all_ptr_ == opt))
                throw OptionAlreadyAdded("cannot move help options");

            if (config_ptr_ == opt)
                throw OptionAlreadyAdded("cannot move config file options");

            auto iterator =
                std::find_if(std::begin(options_), std::end(options_), [opt](const Option_p& v) { return v.get() == opt; });
            if (iterator != std::end(options_))
            {
                const auto& opt_p = *iterator;
                if (std::find_if(std::begin(app->options_), std::end(app->options_), [&opt_p](const Option_p& v) {
                        return (*v == *opt_p);
                    }) == std::end(app->options_))
                {
                    // only erase after the insertion was successful
                    app->options_.push_back(std::move(*iterator));
                    options_.erase(iterator);
                }
                else
                {
                    throw OptionAlreadyAdded(opt->get_name());
                }
            }
            else
            {
                throw OptionNotFound("could not locate the given App");
            }
        }
    };

    /// Extension of App to better manage groups of options
    class Option_group : public App
    {
    public:
        Option_group(std::string group_description, std::string group_name, App* parent) :
            App(std::move(group_description), "", parent)
        {
            group(group_name);
            // option groups should have automatic fallthrough
        }
        using App::add_option;
        /// Add an existing option to the Option_group
        Option* add_option(Option* opt)
        {
            if (get_parent() == nullptr)
            {
                throw OptionNotFound("Unable to locate the specified option");
            }
            get_parent()->_move_option(opt, this);
            return opt;
        }
        /// Add an existing option to the Option_group
        void add_options(Option* opt) { add_option(opt); }
        /// Add a bunch of options to the group
        template<typename... Args>
        void add_options(Option* opt, Args... args)
        {
            add_option(opt);
            add_options(args...);
        }
        using App::add_subcommand;
        /// Add an existing subcommand to be a member of an option_group
        App* add_subcommand(App* subcom)
        {
            App_p subc = subcom->get_parent()->get_subcommand_ptr(subcom);
            subc->get_parent()->remove_subcommand(subcom);
            add_subcommand(std::move(subc));
            return subcom;
        }
    };
    /// Helper function to enable one option group/subcommand when another is used
    inline void TriggerOn(App* trigger_app, App* app_to_enable)
    {
        app_to_enable->enabled_by_default(false);
        app_to_enable->disabled_by_default();
        trigger_app->preparse_callback([app_to_enable](size_t) { app_to_enable->disabled(false); });
    }

    /// Helper function to enable one option group/subcommand when another is used
    inline void TriggerOn(App* trigger_app, std::vector<App*> apps_to_enable)
    {
        for (auto& app : apps_to_enable)
        {
            app->enabled_by_default(false);
            app->disabled_by_default();
        }

        trigger_app->preparse_callback([apps_to_enable](size_t) {
            for (auto& app : apps_to_enable)
            {
                app->disabled(false);
            }
        });
    }

    /// Helper function to disable one option group/subcommand when another is used
    inline void TriggerOff(App* trigger_app, App* app_to_enable)
    {
        app_to_enable->disabled_by_default(false);
        app_to_enable->enabled_by_default();
        trigger_app->preparse_callback([app_to_enable](size_t) { app_to_enable->disabled(); });
    }

    /// Helper function to disable one option group/subcommand when another is used
    inline void TriggerOff(App* trigger_app, std::vector<App*> apps_to_enable)
    {
        for (auto& app : apps_to_enable)
        {
            app->disabled_by_default(false);
            app->enabled_by_default();
        }

        trigger_app->preparse_callback([apps_to_enable](size_t) {
            for (auto& app : apps_to_enable)
            {
                app->disabled();
            }
        });
    }

    namespace FailureMessage
    {
        /// Printout a clean, simple message on error (the default in CLI11 1.5+)
        inline std::string simple(const App* app, const Error& e)
        {
            std::string header = std::string(e.what()) + "\n";
            std::vector<std::string> names;

            // Collect names
            if (app->get_help_ptr() != nullptr)
                names.push_back(app->get_help_ptr()->get_name());

            if (app->get_help_all_ptr() != nullptr)
                names.push_back(app->get_help_all_ptr()->get_name());

            // If any names found, suggest those
            if (!names.empty())
                header += "Run with " + detail::join(names, " or ") + " for more information.\n";

            return header;
        }

        /// Printout the full help string on error (if this fn is set, the old default for CLI11)
        inline std::string help(const App* app, const Error& e)
        {
            std::string header = std::string("ERROR: ") + e.get_name() + ": " + e.what() + "\n";
            header += app->help();
            return header;
        }

    } // namespace FailureMessage

    namespace detail
    {
        /// This class is simply to allow tests access to App's protected functions
        struct AppFriend
        {
            /// Wrap _parse_short, perfectly forward arguments and return
            template<typename... Args>
            static auto parse_arg(App* app, Args&&... args) ->
                typename std::result_of<decltype (&App::_parse_arg)(App, Args...)>::type
            {
                return app->_parse_arg(std::forward<Args>(args)...);
            }

            /// Wrap _parse_subcommand, perfectly forward arguments and return
            template<typename... Args>
            static auto parse_subcommand(App* app, Args&&... args) ->
                typename std::result_of<decltype (&App::_parse_subcommand)(App, Args...)>::type
            {
                return app->_parse_subcommand(std::forward<Args>(args)...);
            }
            /// Wrap the fallthrough parent function to make sure that is working correctly
            static App* get_fallthrough_parent(App* app) { return app->_get_fallthrough_parent(); }
        };
    } // namespace detail

} // namespace CLI

// From CLI/Config.hpp:

namespace CLI
{
    inline std::string
    ConfigINI::to_config(const App* app, bool default_also, bool write_description, std::string prefix) const
    {
        std::stringstream out;
        for (const Option* opt : app->get_options({}))
        {
            // Only process option with a long-name and configurable
            if (!opt->get_lnames().empty() && opt->get_configurable())
            {
                std::string name = prefix + opt->get_lnames()[0];
                std::string value;

                // Non-flags
                if (opt->get_type_size() != 0)
                {
                    // If the option was found on command line
                    if (opt->count() > 0)
                        value = detail::ini_join(opt->results());

                    // If the option has a default and is requested by optional argument
                    else if (default_also && !opt->get_default_str().empty())
                        value = opt->get_default_str();
                    // Flag, one passed
                }
                else if (opt->count() == 1)
                {
                    value = "true";

                    // Flag, multiple passed
                }
                else if (opt->count() > 1)
                {
                    value = std::to_string(opt->count());

                    // Flag, not present
                }
                else if (opt->count() == 0 && default_also)
                {
                    value = "false";
                }

                if (!value.empty())
                {
                    if (write_description && opt->has_description())
                    {
                        if (static_cast<int>(out.tellp()) != 0)
                        {
                            out << std::endl;
                        }
                        out << "; " << detail::fix_newlines("; ", opt->get_description()) << std::endl;
                    }

                    // Don't try to quote anything that is not size 1
                    if (opt->get_items_expected() != 1)
                        out << name << "=" << value << std::endl;
                    else
                        out << name << "=" << detail::add_quotes_if_needed(value) << std::endl;
                }
            }
        }

        for (const App* subcom : app->get_subcommands({}))
            out << to_config(subcom, default_also, write_description, prefix + subcom->get_name() + ".");

        return out.str();
    }

} // namespace CLI

// From CLI/Formatter.hpp:

namespace CLI
{
    inline std::string
    Formatter::make_group(std::string group, bool is_positional, std::vector<const Option*> opts) const
    {
        std::stringstream out;

        out << "\n"
            << group << ":\n";
        for (const Option* opt : opts)
        {
            out << make_option(opt, is_positional);
        }

        return out.str();
    }

    inline std::string Formatter::make_positionals(const App* app) const
    {
        std::vector<const Option*> opts =
            app->get_options([](const Option* opt) { return !opt->get_group().empty() && opt->get_positional(); });

        if (opts.empty())
            return std::string();
        else
            return make_group(get_label("Positionals"), true, opts);
    }

    inline std::string Formatter::make_groups(const App* app, AppFormatMode mode) const
    {
        std::stringstream out;
        std::vector<std::string> groups = app->get_groups();

        // Options
        for (const std::string& group : groups)
        {
            std::vector<const Option*> opts = app->get_options([app, mode, &group](const Option* opt) {
                return opt->get_group() == group // Must be in the right group
                       && opt->nonpositional() // Must not be a positional
                       && (mode != AppFormatMode::Sub // If mode is Sub, then
                           || (app->get_help_ptr() != opt // Ignore help pointer
                               && app->get_help_all_ptr() != opt)); // Ignore help all pointer
            });
            if (!group.empty() && !opts.empty())
            {
                out << make_group(group, false, opts);

                if (group != groups.back())
                    out << "\n";
            }
        }

        return out.str();
    }

    inline std::string Formatter::make_description(const App* app) const
    {
        std::string desc = app->get_description();
        auto min_options = app->get_require_option_min();
        auto max_options = app->get_require_option_max();
        if (app->get_required())
        {
            desc += " REQUIRED ";
        }
        if ((max_options == min_options) && (min_options > 0))
        {
            if (min_options == 1)
            {
                desc += " \n[Exactly 1 of the following options is required]";
            }
            else
            {
                desc += " \n[Exactly " + std::to_string(min_options) + "options from the following list are required]";
            }
        }
        else if (max_options > 0)
        {
            if (min_options > 0)
            {
                desc += " \n[Between " + std::to_string(min_options) + " and " + std::to_string(max_options) +
                        " of the follow options are required]";
            }
            else
            {
                desc += " \n[At most " + std::to_string(max_options) + " of the following options are allowed]";
            }
        }
        else if (min_options > 0)
        {
            desc += " \n[At least " + std::to_string(min_options) + " of the following options are required]";
        }
        return (!desc.empty()) ? desc + "\n" : std::string{};
    }

    inline std::string Formatter::make_usage(const App* app, std::string name) const
    {
        std::stringstream out;

        out << get_label("Usage") << ":" << (name.empty() ? "" : " ") << name;

        std::vector<std::string> groups = app->get_groups();

        // Print an Options badge if any options exist
        std::vector<const Option*> non_pos_options =
            app->get_options([](const Option* opt) { return opt->nonpositional(); });
        if (!non_pos_options.empty())
            out << " [" << get_label("OPTIONS") << "]";

        // Positionals need to be listed here
        std::vector<const Option*> positionals = app->get_options([](const Option* opt) { return opt->get_positional(); });

        // Print out positionals if any are left
        if (!positionals.empty())
        {
            // Convert to help names
            std::vector<std::string> positional_names(positionals.size());
            std::transform(positionals.begin(), positionals.end(), positional_names.begin(), [this](const Option* opt) {
                return make_option_usage(opt);
            });

            out << " " << detail::join(positional_names, " ");
        }

        // Add a marker if subcommands are expected or optional
        if (!app->get_subcommands(
                    [](const CLI::App* subc) { return ((!subc->get_disabled()) && (!subc->get_name().empty())); })
                 .empty())
        {
            out << " " << (app->get_require_subcommand_min() == 0 ? "[" : "")
                << get_label(app->get_require_subcommand_max() < 2 || app->get_require_subcommand_min() > 1 ? "SUBCOMMAND" : "SUBCOMMANDS")
                << (app->get_require_subcommand_min() == 0 ? "]" : "");
        }

        out << std::endl;

        return out.str();
    }

    inline std::string Formatter::make_footer(const App* app) const
    {
        std::string footer = app->get_footer();
        if (!footer.empty())
            return footer + "\n";
        else
            return "";
    }

    inline std::string Formatter::make_help(const App* app, std::string name, AppFormatMode mode) const
    {
        // This immediately forwards to the make_expanded method. This is done this way so that subcommands can
        // have overridden formatters
        if (mode == AppFormatMode::Sub)
            return make_expanded(app);

        std::stringstream out;
        if ((app->get_name().empty()) && (app->get_parent() != nullptr))
        {
            if (app->get_group() != "Subcommands")
            {
                out << app->get_group() << ':';
            }
        }

        out << make_description(app);
        out << make_usage(app, name);
        out << make_positionals(app);
        out << make_groups(app, mode);
        out << make_subcommands(app, mode);
        out << make_footer(app);

        return out.str();
    }

    inline std::string Formatter::make_subcommands(const App* app, AppFormatMode mode) const
    {
        std::stringstream out;

        std::vector<const App*> subcommands = app->get_subcommands({});

        // Make a list in definition order of the groups seen
        std::vector<std::string> subcmd_groups_seen;
        for (const App* com : subcommands)
        {
            if (com->get_name().empty())
            {
                out << make_expanded(com);
                continue;
            }
            std::string group_key = com->get_group();
            if (!group_key.empty() &&
                std::find_if(subcmd_groups_seen.begin(), subcmd_groups_seen.end(), [&group_key](std::string a) {
                    return detail::to_lower(a) == detail::to_lower(group_key);
                }) == subcmd_groups_seen.end())
                subcmd_groups_seen.push_back(group_key);
        }

        // For each group, filter out and print subcommands
        for (const std::string& group : subcmd_groups_seen)
        {
            out << "\n"
                << group << ":\n";
            std::vector<const App*> subcommands_group = app->get_subcommands(
                [&group](const App* sub_app) { return detail::to_lower(sub_app->get_group()) == detail::to_lower(group); });
            for (const App* new_com : subcommands_group)
            {
                if (new_com->get_name().empty())
                    continue;
                if (mode != AppFormatMode::All)
                {
                    out << make_subcommand(new_com);
                }
                else
                {
                    out << new_com->help(new_com->get_name(), AppFormatMode::Sub);
                    out << "\n";
                }
            }
        }

        return out.str();
    }

    inline std::string Formatter::make_subcommand(const App* sub) const
    {
        std::stringstream out;
        detail::format_help(out, sub->get_name(), sub->get_description(), column_width_);
        return out.str();
    }

    inline std::string Formatter::make_expanded(const App* sub) const
    {
        std::stringstream out;
        out << sub->get_display_name() << "\n";

        out << make_description(sub);
        out << make_positionals(sub);
        out << make_groups(sub, AppFormatMode::Sub);
        out << make_subcommands(sub, AppFormatMode::Sub);

        // Drop blank spaces
        std::string tmp = detail::find_and_replace(out.str(), "\n\n", "\n");
        tmp = tmp.substr(0, tmp.size() - 1); // Remove the final '\n'

        // Indent all but the first line (the name)
        return detail::find_and_replace(tmp, "\n", "\n  ") + "\n";
    }

    inline std::string Formatter::make_option_name(const Option* opt, bool is_positional) const
    {
        if (is_positional)
            return opt->get_name(true, false);
        else
            return opt->get_name(false, true);
    }

    inline std::string Formatter::make_option_opts(const Option* opt) const
    {
        std::stringstream out;

        if (opt->get_type_size() != 0)
        {
            if (!opt->get_type_name().empty())
                out << " " << get_label(opt->get_type_name());
            if (!opt->get_default_str().empty())
                out << "=" << opt->get_default_str();
            if (opt->get_expected() > 1)
                out << " x " << opt->get_expected();
            if (opt->get_expected() == -1)
                out << " ...";
            if (opt->get_required())
                out << " " << get_label("REQUIRED");
        }
        if (!opt->get_envname().empty())
            out << " (" << get_label("Env") << ":" << opt->get_envname() << ")";
        if (!opt->get_needs().empty())
        {
            out << " " << get_label("Needs") << ":";
            for (const Option* op : opt->get_needs())
                out << " " << op->get_name();
        }
        if (!opt->get_excludes().empty())
        {
            out << " " << get_label("Excludes") << ":";
            for (const Option* op : opt->get_excludes())
                out << " " << op->get_name();
        }
        return out.str();
    }

    inline std::string Formatter::make_option_desc(const Option* opt) const { return opt->get_description(); }

    inline std::string Formatter::make_option_usage(const Option* opt) const
    {
        // Note that these are positionals usages
        std::stringstream out;
        out << make_option_name(opt, true);

        if (opt->get_expected() > 1)
            out << "(" << std::to_string(opt->get_expected()) << "x)";
        else if (opt->get_expected() < 0)
            out << "...";
        return opt->get_required() ? out.str() : "[" + out.str() + "]";
    }

} // namespace CLI