parseDuration function
Implementation
Duration parseDuration(String? s) {
if (s == null) return Duration.zero;
if (s.contains(':') == false) return Duration.zero;
List<String> parts = s.split(':');
if (parts[1].length != 2) return Duration.zero;
int hours = 0;
int minutes = 0;
hours = int.parse(parts[0]);
minutes = int.parse(parts[1]);
return Duration(hours: hours, minutes: minutes);
}