anchor.diff:    }
   
     Widget _buildRow(WordPair pair) {
  +    final alreadySaved = _saved.contains(pair);
       return ListTile(
         title: Text(
           pair.asPascalCase,
           style: _biggerFont,
         ),
  +      trailing: Icon(
  +        alreadySaved ? Icons.favorite : Icons.favorite_border,
  +        color: alreadySaved ? Colors.red : null,
  +      ),
  +      onTap: () {
  +        setState(() {
  +          if (alreadySaved) {
  +            _saved.remove(pair);
  +          } else {
  +            _saved.add(pair);
  +          }
  +        });
  +      },
       );
     }
   
  
positive.code:   Widget build(BuildContext context) {
      return MaterialApp(
        title: 'Startup Name Generator',
        home: RandomWords(),
      );
    }
  
negative.code: 
  class RandomWordsState extends State<RandomWords> {
    final _suggestions = <WordPair>[];
    final _saved = Set<WordPair>();
    final _biggerFont = const TextStyle(fontSize: 18.0);
  
    Widget _buildSuggestions() {
  