anchor.diff:  
       _setupTabController();
   
  -    _pageIdSubscription =
  -        frameworkController.onShowPageId.listen(_pushScreenByPageId);
  +    _showPageSubscription =
  +        frameworkController.onShowPageId.listen(_showPageById);
     }
   
     @override
  
positive.code:     });
    }
  
    /// Push the given page ID into the navigation history.
    void _pushScreenByPageId(String pageId) {
      final previousTabIndex = _tabController.previousIndex;
  
      final screen = widget.tabs
          .firstWhere((screen) => screen.screenId == pageId, orElse: () => null);
      final newIndex = screen == null ? -1 : widget.tabs.indexOf(screen);
  
      if (newIndex != -1 && newIndex != previousTabIndex) {
        ModalRoute.of(context).addLocalHistoryEntry(LocalHistoryEntry(
          onRemove: () {
            if (widget.tabs.length >= previousTabIndex) {
              _tabController.animateTo(previousTabIndex);
            }
          },
        ));
      }
    }
  
  
negative.code: 
    ImportController _importController;
  
    StreamSubscription<String> _showPageSubscription;
  
    @override
    void initState() {
  