AsyncLazy<T> v1

AsyncLazy<T>.v1.cs

// https://blogs.msdn.microsoft.com/pfxteam/2011/01/15/asynclazyt/

public class AsyncLazy<T> : Lazy<Task<T>> 
{ 
    public AsyncLazy(Func<T> valueFactory) : 
        base(() => Task.Factory.StartNew(valueFactory)) { }
    public AsyncLazy(Func<Task<T>> taskFactory) : 
        base(() => Task.Factory.StartNew(() => taskFactory()).Unwrap()) { } 

    public TaskAwaiter<T> GetAwaiter() { return Value.GetAwaiter(); } 
}