Actions.cs

public class Testclass {  
  Action<bool> MyAction { get; set; }
  Func<Task<bool>> MyAwaitedAction { get; set; }
  public async Task AsyncTestMethod()
  {
    MyAction += (result) => {
      Console.WriteLine(result);
    };

    MyAwaitedAction += () => {
      return Task.FromResult(true);
    };

    MyAwaitedAction += () => {
      return Task.FromResult(false);
    };

    //Wait until the action completes.
    //Only the last subscribed function will return;
    var result = await MyAwaitedAction();
    MyAction.Invoke(result);
  }
}