anchor.diff:      title: Text(widget.title),
     ),
     body: Center(
  -    mainAxisAlignment: MainAxisAlignment.center,
  +    widthFactor: 0.5,
       child: Column(
  +      mainAxisAlignment: MainAxisAlignment.center,
         children: <Widget>[
           Text(
             'You have pushed the button this many times:',
  
positive.code:          ),
        ],
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    ),
  );
  ```
  
negative.code:       ],
        mainAxisAlignment: MainAxisAlignment.center,
      ),
      widthFactor: 0.5,
    ),
    floatingActionButton: FloatingActionButton(
      child: Icon(Icons.add),
      onPressed: _incrementCounter,
      tooltip: 'Increment',
    ),
  );
  ```
  