code: func newSeparatedString(commaSeparated string) separatedString {
  	if strings.TrimSpace(commaSeparated) == "" {
  		return nil
  	}
  	split := strings.Split(commaSeparated, ",")
  	var ss []string
  	for i, tag := range split {
  		split[i] = strings.TrimSpace(tag)
  		if split[i] != "" {
  			ss = append(ss, split[i])
  		}
  	}
  	if !sort.StringsAreSorted(ss) {
  		sort.Strings(ss)
  	}
  	return ss
  }
docs: // newSeparatedString returns a newly created SeparatedString value from the string given.
  // There is no error if the string does not include a comma.