code: func (q *TagQuery) getInitialByTagMatch(idCh chan schema.MKey, stopCh chan struct{}) {
  	defer q.wg.Done()
  
  TAGS:
  	for tag, values := range q.index {
  		if q.tagMatch.value.MatchString(tag) {
  			for _, ids := range values {
  				for id := range ids {
  					select {
  					case <-stopCh:
  						break TAGS
  					case idCh <- id:
  					}
  				}
  			}
  		}
  	}
  
  	close(idCh)
  }
docs: // getInitialByTagMatch generates the initial resultset by creating a list of
  // metric IDs of which at least one tag matches the defined regex