anchor.diff:    /// The animation curve to use when animating to a given page.
     final Curve curve;
   
  -  int get _itemCount;
  +  /// The number of items, one per page, to display.
  +  int get itemCount;
   }
   
   /// A widget that pages through an iterable list of children.
  
positive.code:   final Iterable<Widget> children;
  
    @override
    int get _itemCount => children?.length ?? 0;
  
    @override
    PageableListState<PageableList> createState() => new PageableListState<PageableList>();
  
negative.code: 
    @override
    double pixelOffsetToScrollOffset(double pixelOffset) {
      final double unit = pixelsPerScrollUnit;
      return super.pixelOffsetToScrollOffset(unit == 0.0 ? 0.0 : pixelOffset / unit);
    }
  
    @override
    double scrollOffsetToPixelOffset(double scrollOffset) {
      return super.scrollOffsetToPixelOffset(scrollOffset * pixelsPerScrollUnit);
    }
  
    int _scrollOffsetToPageIndex(double scrollOffset) {
  