code: func (kz *Kazoo) WatchTopics() (TopicList, <-chan zk.Event, error) {
  	root := fmt.Sprintf("%s/brokers/topics", kz.conf.Chroot)
  	children, _, c, err := kz.conn.ChildrenW(root)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	result := make(TopicList, 0, len(children))
  	for _, name := range children {
  		result = append(result, kz.Topic(name))
  	}
  	return result, c, nil
  }
docs: // WatchTopics returns a list of all registered Kafka topics, and
  // watches that list for changes.