anchor.diff:  ///    Navigator.of(context).push(MaterialPageRoute(
   ///      builder: (BuildContext context) => Scaffold(
   ///        appBar: AppBar(
  -///          title: Text('second Page'),
  +///          title: const Text('second Page'),
   ///        ),
   ///        body: Center(
   ///          child: Column(
  
positive.code: ///            child: _blueRectangle(Size(50,50)),
  ///          ),
  ///          onTap: () => _gotoDetailsPage(context),
  ///          title: Text('Tap on the icon to view hero animation transition.'),
  ///        ),
  ///      ],
  ///    );
  
negative.code: ///    return Column(
  ///      crossAxisAlignment: CrossAxisAlignment.start,
  ///      children: <Widget>[
  ///        const SizedBox(
  ///          height: 20.0,
  ///        ),
  ///        ListTile(
  