durationToString function
Returns the given duration in H:MM:SS format.
Implementation
String durationToString(Duration duration) {
final String seconds = _twoDigitDuration(duration.inSeconds.remainder(60));
final String minutes = _twoDigitDuration(duration.inMinutes.remainder(60));
final String hours = duration.inHours.toString();
// remove the hour part if there isn't any
if (hours == '0') {
return '$minutes:$seconds';
} else {
return '$hours:$minutes:$seconds';
}
}