getDuration method
Implementation
String getDuration(Duration duration) {
String twoDigits(int n) => n.toString().padLeft(2, '0');
final String twoDigitMinutes = twoDigits(duration.inMinutes.remainder(60));
final String twoDigitSeconds = twoDigits(duration.inSeconds.remainder(60));
return '$twoDigitMinutes:$twoDigitSeconds';
}