code: func (el *CallbackEventListener) RegPromotions(f PromotionReattachmentEventCallback) {
  	el.ids = append(el.ids, el.em.RegisterListener(func(data interface{}) {
  		f(data.(*promoter.PromotionReattachmentEvent))
  	}, promoter.EventPromotion))
  }
docs: // RegPromotions registers the given callback to execute on promotions.