=== tests/cases/compiler/interfaceSubtyping.ts ===
interface iface {
>iface : iface

    foo(): void;
>foo : () => void
}
class Camera implements iface{
>Camera : Camera
>iface : iface

    constructor (public str: string) {
>str : string
    }
    foo() {  return "s";   }
>foo : () => string
}