/**
  * Delete a to-do list category using ajax
  * @static
  */
 public static function delete_category_callback()
 {
     check_ajax_referer('cleverness-todo-cat');
     $permission = CTDL_Lib::check_permission('category', 'add_cat');
     $status = $permission === true ? CTDL_Categories::delete_category() : 2;
     echo $status;
     die;
     // this is required to return a proper result
 }