anchor.diff:  import 'scaffold.dart';
   import 'theme_data.dart';
   import 'theme.dart';
  -import 'typography.dart';
   
   // https://material.google.com/components/snackbars-toasts.html#snackbars-toasts-specs
   const double _kSnackBarPadding = 24.0;
  
positive.code:   @override
    Widget build(BuildContext context) {
      assert(animation != null);
      List<Widget> children = <Widget>[
        const SizedBox(width: _kSnackBarPadding),
        new Flexible(
          child: new Container(
            padding: const EdgeInsets.symmetric(vertical: _kSingleLineVerticalPadding),
            child: new DefaultTextStyle(
              style: Typography.white.subhead,
              child: content
            )
          )
  
negative.code:               elevation: 6,
                color: _kSnackBackground,
                child: new Theme(
                  data: darkTheme,
                  child: new FadeTransition(
                    opacity: fadeAnimation,
                    child: new Row(
  