code: func (s *ticketStore) removeRegisterTopic(topic Topic) {
  	log.Trace("Removing discovery topic", "topic", topic)
  	if s.tickets[topic] == nil {
  		log.Warn("Removing non-existent discovery topic", "topic", topic)
  		return
  	}
  	for _, list := range s.tickets[topic].buckets {
  		for _, ref := range list {
  			ref.t.refCnt--
  			if ref.t.refCnt == 0 {
  				delete(s.nodes, ref.t.node)
  				delete(s.nodeLastReq, ref.t.node)
  			}
  		}
  	}
  	delete(s.tickets, topic)
  }
docs: // removeRegisterTopic deletes all tickets for the given topic.