start method
- required String title,
- required Duration duration,
Starts a new timer with the given title and duration. Cancels any previous timer.
Implementation
void start({required String title, required Duration duration}) {
cancel();
isPaused = false;
this.title = title;
timeLeft = duration;
_timer = Timer.periodic(const Duration(seconds: 1), _update);
notifyListeners();
}