code: public <T> AskFuture<T> ask(ActorSelection selection, long timeout, AskCallback<T> callback) {
          return askPattern.ask(system().actorOf(selection), timeout, callback);
      }
docs: Ask TaskActor for result
  
  @param selection ActorSelection of task
  @param timeout   timeout of task
  @param callback  callback for ask
  @return Future