anchor.diff:  ///         ),
   ///       ),
   ///     ],
  +///   ),
  +/// )
  +/// ```
  +/// {@end-tool}
  +///
  +/// {@tool snippet}
  +///
  +/// This example of a [Container] wraps a [GestureDetector] widget.
  +/// Since the [GestureDetector] does not have a child it takes on the size of
  +/// its parent making the entire area of the surrounding [Container] clickable.
  +/// When tapped the [Container] turns yellow by setting the `_color` field:
  +///
  +/// ```dart
  +/// Container(
  +///   color: _color,
  +///   height: 200.0,
  +///   width: 200.0,
  +///   child: GestureDetector(
  +///     onTap: () {
  +///       setState(() {
  +///         _color = Colors.yellow;
  +///       });
  +///     },
   ///   ),
   /// )
   /// ```
  
positive.code: ///
  /// {@tool snippet}
  ///
  /// This example turns the light bulb yellow when the "turn lights on" button is
  /// tapped by setting the `_lights` field:
  ///
  /// ```dart
  /// Container(
  
negative.code: // bool _lights;
  // void setState(VoidCallback fn) { }
  // String _last;
  // Color _color;
  
  /// Factory for creating gesture recognizers.
  ///
  