flutter-state-ex-1.dart

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
    Widget build(BuildContext context) {
      // here's where the UI tree is built and returned
    }
 }