code: func (e *EventListener) Unsubscribe(s *EventSubscriber) {
  	e.subMtx.Lock()
  	defer e.subMtx.Unlock()
  	if subs, ok := e.subscribers[s.appID]; ok {
  		delete(subs, s)
  		if len(subs) == 0 {
  			delete(e.subscribers, s.appID)
  		}
  	}
  }
docs: // Unsubscribe unsubscribes the given subscriber.