code: func (e *engineImpl) PullPubSubOnDevServer(c context.Context, taskManagerName, publisher string) error {
  	_, sub := e.genTopicAndSubNames(c, taskManagerName, publisher)
  	msg, ack, err := pullSubcription(c, sub, "")
  	if err != nil {
  		return err
  	}
  	if msg == nil {
  		logging.Infof(c, "No new PubSub messages")
  		return nil
  	}
  	switch err = e.handlePubSubMessage(c, msg); {
  	case err == nil:
  		ack() // success
  	case transient.Tag.In(err) || tq.Retry.In(err):
  		// don't ack, ask for redelivery
  	default:
  		ack() // fatal error
  	}
  	return err
  }
docs: // PullPubSubOnDevServer is called on dev server to pull messages from PubSub
  // subscription associated with given publisher.
  //
  // Part of the internal interface, doesn't check ACLs.