timer.dart

import 'dart:async';

void main() {
  
  var duration = Duration(milliseconds: 500);
  
  var t = Timer.periodic(duration, (Timer t) {
    print('Update ${t}');
  });
  print(t.isActive);
  
  var d2 = Duration(seconds: 2);
  Timer(d2, () {
    t.cancel();
    print(t.isActive);
  });
}