anchor.diff:      _appState.viewingBooks = true;
     }
   
  -  void _handleLoggedIn() {
  -    _appState.isLoggedIn = true;
  +  Future _handleLoggedIn(Credentials credentials) async {
  +    await _appState.signIn(credentials.username, credentials.password);
     }
   }
   
  
positive.code:   runApp(BooksApp());
  }
  
  class BooksApp extends StatefulWidget {
    @override
    State<StatefulWidget> createState() => _BooksAppState();
  }
  
  class AppState extends ChangeNotifier {
    bool _isLoggedIn = false;
  
    bool get isLoggedIn => _isLoggedIn;
  
    set isLoggedIn(bool value) {
      _isLoggedIn = value;
      notifyListeners();
    }
  
    bool _viewingBooks = false;
  
negative.code:     } else if (path is LoginRoutePath) {
        // Log out
        _appState.viewingBooks = false;
        _appState.auth.signOut();
      }
    }
  
  