formatDateTime method
Implementation
String formatDateTime({bool persianDigits = false}) {
final JalaliFormatter f = formatter;
final String result = '${f.yyyy}-${f.mm}-${f.dd} ${hour.toString().padLeft(2, '0')}:${minute.toString().padLeft(2, '0')}:${second.toString().padLeft(2, '0')}';
return persianDigits ? f.toPersian(result) : result;
}