private IEnumerable<ViewModel> RecurseListLayout(ListLayout layout)
        {
            IEnumerable<ViewModel> layoutElements = Enumerable.Empty<ViewModel>();

            foreach (var element in layout.Elements)
            {
                layoutElements = layoutElements.Concat(VisitLayoutItem(element));
            }

            return layoutElements;
        }
        private IEnumerable <ViewModel> RecurseListLayout(ListLayout layout)
        {
            IEnumerable <ViewModel> layoutElements = Enumerable.Empty <ViewModel>();

            foreach (var element in layout.Elements)
            {
                layoutElements = layoutElements.Concat(VisitLayoutItem(element));
            }

            return(layoutElements);
        }