code: func NewKVListQuery(s string) (*KVListQuery, error) {
  	if s != "" && !KVListQueryRe.MatchString(s) {
  		return nil, fmt.Errorf("kv.list: invalid format: %q", s)
  	}
  
  	m := regexpMatch(KVListQueryRe, s)
  	return &KVListQuery{
  		stopCh: make(chan struct{}, 1),
  		dc:     m["dc"],
  		prefix: m["prefix"],
  	}, nil
  }
docs: // NewKVListQuery parses a string into a dependency.