Простейшая реализация шаблона await

public class MyAwaitableType

{

public MinimalAwaiter GetAwaiter()

{

return new MinimalAwaiter();

}

public class MinimalAwaiter : INotifyCompletion

{

public bool IsCompleted => true;

public string GetResult() => "This is a result";

public void OnCompleted(Action continuation)

{

throw new NotImplementedException();

}

}

}