toHHMMSS method
Implementation
String toHHMMSS() {
String two(int n) => n.toString().padLeft(2, '0');
final h = inHours;
final m = inMinutes.remainder(60);
final s = inSeconds.remainder(60);
return h > 0 ? "${two(h)}:${two(m)}:${two(s)}" : "${two(m)}:${two(s)}";
}