[documentation] provide code sample for MergeSemantics #22782
Description
Whether each widget sample API docs provide sample code ?
For example, this:
https://docs.flutter.io/flutter/widgets/Row-class.html
new Row(
children: <Widget>[
new Expanded(
child: new Text('Deliver features faster', textAlign: TextAlign.center),
),
new Expanded(
child: new Text('Craft beautiful UIs', textAlign: TextAlign.center),
),
new Expanded(
child: new FittedBox(
fit: BoxFit.contain, // otherwise the logo will be tiny
child: const FlutterLogo(),
),
),
],
)But some of them are not, for example:
https://docs.flutter.io/flutter/widgets/MergeSemantics-class.html
So, we hope the offical site provide all of them and easily to find out how to use them, and can each widget provide a corresponding GIF animation display what their running effects?