anchor.diff:      assert(destination != null && destination.isValid);
     }
   
  +  static final double height = 328.0;
     final TravelDestination destination;
  +
   
     @override
     Widget build(BuildContext context) {
  
positive.code:       appBar: new AppBar(
          title: new Text('Travel stream')
        ),
        body: new Block(
          padding: const EdgeInsets.only(top: 8.0, left: 8.0, right: 8.0),
          children: destinations.map((TravelDestination destination) {
            return new Container(
  
negative.code:     TextStyle descriptionStyle = theme.textTheme.subhead;
      TextStyle buttonStyle = theme.textTheme.button.copyWith(color: theme.primaryColor);
  
      return new SizedBox(
        height: height,
        child: new Card(
          child: new Column(
            children: <Widget>[
              // photo and title
  