StreamClass.forEach<S>(source: Source<S>,fn: (value: Exclude<S, AnyFailure>,index: number) => void | PromiseLike<void>): Task<void, Extract<S, AnyFailure>>
StreamClass#forEach as a static: Stream.forEach(source, …) is
Stream.from(source).forEach(…).
await Stream.forEach([1, 2], () => {}); // undefined