formatDurationInHhMmSs method
Implementation
String formatDurationInHhMmSs(Duration duration) {
final hh = (duration.inHours).toString().padLeft(2, '0');
final mm = (duration.inMinutes % 60).toString().padLeft(2, '0');
final ss = (duration.inSeconds % 60).toString().padLeft(2, '0');
return '$hh:$mm:$ss';
}