anchor.diff:    final Iterable<Widget> children;
   
     @override
  -  int get _itemCount => children?.length ?? 0;
  +  int get itemCount => children?.length ?? 0;
   
     @override
     PageableListState<PageableList> createState() => new PageableListState<PageableList>();
  
positive.code:   );
  
    /// The total number of list items.
    final int itemCount;
  
    /// A function that returns the pages themselves.
    final ItemListBuilder itemBuilder;
  
    @override
    int get _itemCount => itemCount ?? 0;
  
    @override
    _PageableLazyListState createState() => new _PageableLazyListState();
  }
  
  
negative.code: ///
  /// Subclasses typically override [buildContent] to build viewports.
  abstract class PageableState<T extends Pageable> extends ScrollableState<T> {
    int get _itemCount => config.itemCount;
    int _previousItemCount;
  
    /// Convert from the item based scroll units to logical pixels.
    double get pixelsPerScrollUnit {
      final RenderBox box = context.findRenderObject();
      if (box == null || !box.hasSize)
        return 0.0;
  