code: func (q *mergeQuerier) LabelValues(name string) ([]string, error) {
  	var results [][]string
  	for _, querier := range q.queriers {
  		values, err := querier.LabelValues(name)
  		if err != nil {
  			return nil, err
  		}
  		results = append(results, values)
  	}
  	return mergeStringSlices(results), nil
  }
docs: // LabelValues returns all potential values for a label name.