code: func joinFold(ss []string, sep string, foldWidth int) string {
  	tmpWidth := 0
  	var out []string
  	for _, s := range ss {
  		tmpWidth += len(s)
  		if tmpWidth >= foldWidth {
  			out = append(out, fmt.Sprintf("%s%s\n", s, sep))
  			tmpWidth = 0
  			continue
  		}
  		out = append(out, fmt.Sprintf("%s%s ", s, sep))
  	}
  	return strings.Join(out, "")
  }
docs: /////////////////////////////// Utility function ///////////////////////////////