anchor.diff:  }
   
   class _BooleanItem extends StatelessWidget {
  -  const _BooleanItem(this.title, this.value, this.onChanged);
  +  const _BooleanItem(this.title, this.value, this.onChanged, { this.switchKey });
   
     final String title;
     final bool value;
     final ValueChanged<bool> onChanged;
  +  // [switchKey] is used for accessing the switch from driver tests.
  +  final Key switchKey;
   
     @override
     Widget build(BuildContext context) {
  
positive.code:           ),
          );
        },
      );
    }
  }
  
negative.code:         children: <Widget>[
            new Expanded(child: new Text(title)),
            new Switch(
              key: switchKey,
              value: value,
              onChanged: onChanged,
              activeColor: const Color(0xFF39CEFD),
  