/**
  * Delete To-Do Ajax
  * @static
  */
 public static function delete_todo_callback()
 {
     check_ajax_referer('ctdl-todo');
     $permission = CTDL_Lib::check_permission('todo', 'delete');
     $status = $permission === true ? CTDL_Lib::delete_todo(absint($_POST['cleverness_todo_id'])) : -1;
     echo $status;
     die;
     // this is required to return a proper result
 }