code: func Outputers() []string {
  	outputersMu.Lock()
  	defer outputersMu.Unlock()
  	var list []string
  	for name := range outputers {
  		list = append(list, name)
  	}
  	sort.Strings(list)
  	return list
  }
docs: // Outputers returns a sorted list of the names of the registered outputers.