custom_count.dart

class MyCount extends StatefulWidget {
  @override
  _MyCountState createState() => _MyCountState();
}

class _MyCountState extends State<MyCount> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    // ...
  }
}