code: func (ref *EventClientRef) Unregister(reg fab.Registration) {
  	if service, err := ref.get(); err != nil {
  		logger.Warnf("Error unregistering event registration: %s", err)
  	} else {
  		service.Unregister(reg)
  	}
  }
docs: // Unregister removes the given registration and closes the event channel.