code: func (n *Notifier) NotifyPostTransition(transition *machine.TransitionNotification) (err error) {
  	n.logger.Infof("%s transitioned via event %s: from %s into %s", transition.Machine, transition.Transition, transition.FromState, transition.ToState)
  
  	j, err := json.Marshal(transition)
  	if err != nil {
  		return errors.Wrap(err, "could not JSON encode transition notification")
  	}
  
  	err = n.fw.PublishRaw("choria.machine.transition", j)
  	if err != nil {
  		return errors.Wrap(err, "could not publish notification")
  	}
  
  	return nil
  }
docs: // NotifyPostTransition implements machine.NotificationService