code: func lineSplit(s string, margin int) []string {
  	var ret []string
  	var buf bytes.Buffer
  	for _, r := range s {
  		if r == '\n' {
  			ret = append(ret, stripWhitespace(buf.String(), margin))
  			buf.Reset()
  		} else {
  			buf.WriteRune(r)
  		}
  	}
  	return append(ret, stripWhitespace(buf.String(), margin))
  }
docs: // Split a string by \n and also strip left (up to margin) & right whitespace from each line. */