code: func (el *ChannelEventListener) RegAccountShutdown() *ChannelEventListener {
  	el.Shutdown = make(chan struct{})
  	el.ids = append(el.ids, el.em.RegisterListener(func(data interface{}) {
  		el.Shutdown <- struct{}{}
  	}, event.EventShutdown))
  	return el
  }
docs: // RegAccountShutdown registers this listener to listen for shutdown messages.
  // A shutdown signal is normally only signaled once by the account on it's graceful termination.