在F＃中，异步性是由 async 计算生成器表示的，它并不完全是 Task 的类似物，但通常可以代替以下形式使用：

In F#, asynchrony is represented by the async computation builder, which is not an exact analog of Task, but can generally be used in place of one:

member public this.GetFooAsync (content : byte[]) = 
   async {
      use stream = new MemoryStream(content) 
      return! this.bar.GetFooAsync(stream) |> Async.AwaitTask
   } 
   |> Async.StartAsTask