func FormatRecord(id int64, text []byte) (msg []byte, err error) {
	if !isValidRecordText(text) {
		return nil, errMalformedRecord
	}
	msg = []byte(fmt.Sprintf("%d\n", id))
	msg = append(msg, text...)
	msg = append(msg, '\n')
	return msg, nil
}

// isValidRecordText reports whether text is syntactically valid record text.
func isValidRecordText(text []byte) bool {
	var last rune
	for i := 0; i < len(text); {