code: func (asyncResult *AsyncResult) GetState() *tasks.TaskState {
  	if asyncResult.taskState.IsCompleted() {
  		return asyncResult.taskState
  	}
  
  	taskState, err := asyncResult.backend.GetState(asyncResult.Signature.UUID)
  	if err == nil {
  		asyncResult.taskState = taskState
  	}
  
  	return asyncResult.taskState
  }
docs: // GetState returns latest task state