code: func (cgi *ConsumergroupInstance) Registration() (*Registration, error) {
  	node := fmt.Sprintf("%s/consumers/%s/ids/%s", cgi.cg.kz.conf.Chroot, cgi.cg.Name, cgi.ID)
  	val, _, err := cgi.cg.kz.conn.Get(node)
  	if err != nil {
  		if err == zk.ErrNoNode {
  			return nil, ErrInstanceNotRegistered
  		}
  		return nil, err
  	}
  
  	reg := &Registration{}
  	if err := json.Unmarshal(val, reg); err != nil {
  		return nil, err
  	}
  	return reg, nil
  }
docs: // Registered returns current registration of the consumer group instance.