private async Task InsertTodoItem(TodoItem todoItem)
 {
     // This code inserts a new TodoItem into the database. When the operation completes
     // and Mobile Services has assigned an Id, the item is added to the CollectionView
     await todoTable.InsertAsync(todoItem);
     items.Add(todoItem);
 }
 private async Task UpdateCheckedTodoItem(TodoItem item)
 {
     // This code takes a freshly completed TodoItem and updates the database. When the MobileService 
     // responds, the item is removed from the list 
     await todoTable.UpdateAsync(item);
     items.Remove(item);
    // ListItems.Focus(Windows.UI.Xaml.FocusState.Unfocused);
 }