dotnet-core/release-notes/5.0/netstandard2.1/5.0-preview5_System.Buffers.md

System.Buffers

 namespace System.Buffers {
     public ref struct SequenceReader<T> where T : struct, IEquatable<T> {
+        public ReadOnlySequence<T> UnreadSequence { get; }
+        public void AdvanceToEnd();
+        public bool TryPeek(long offset, out T value);
     }
 }