code: func mapToKV(m map[string]string, joiner string) string {
  	keys := make([]string, 0, len(m))
  	for k := range m {
  		keys = append(keys, k)
  	}
  	sort.Strings(keys)
  
  	r := make([]string, len(keys))
  	for i, k := range keys {
  		r[i] = fmt.Sprintf("%s=%s", k, m[k])
  	}
  	return strings.Join(r, joiner)
  }
docs: // mapToKV converts a map[string]string into a human-friendly key=value list,
  // sorted by name.