fmt function
Implementation
String fmt(Duration d) {
final h = d.inHours;
final m = d.inMinutes.remainder(60);
final s = d.inSeconds.remainder(60);
if (h > 0) {
return '${h.toString().padLeft(2, '0')}:${m.toString().padLeft(2, '0')}:${s.toString().padLeft(2, '0')}';
} else {
return '${m.toString().padLeft(2, '0')}:${s.toString().padLeft(2, '0')}';
}
}