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