public override RenderObject createRenderObject(BuildContext context)
        {
            _SliverPrototypeExtentListElement element = context as _SliverPrototypeExtentListElement;

            return(new _RenderSliverPrototypeExtentList(childManager: element));
        }
 public _RenderSliverPrototypeExtentList(
     _SliverPrototypeExtentListElement childManager = null
     ) : base(childManager: childManager)
 {
 }