How to stop the timer in flutter?

Question

I have created a timer in flutter and everything works fine. Now I can't figure out how to dismiss the timer after I started it.
The docs say that you can cancel it by calling void cancel() but I don't understand the implementation.

How am I supposed to call it?
And is it the right approach?

  static const timeout = const Duration(seconds: 5);
  static const ms = const Duration(milliseconds: 1);

  startTimeout([int milliseconds]) {
    var duration = milliseconds == null ? timeout : ms * milliseconds;
    return new Timer(duration, handleTimeout);
  }

  void handleTimeout() {  // callback function
    Navigator.of(context).pushAndRemoveUntil(new MaterialPageRoute(
        builder: (BuildContext context) => new ScorePage(quiz.score, quiz.length)),(Route route) => route == null);
    return;
  }

Answer 1

Just keep a reference to the time and cancel it when you don't need it anymore

var timer = startTimeout(100);
...
timer.cancel();