public static function get_perms($nid, $args)
 {
     $perms = array();
     if (isset($args['permission_name']) && $args['permission_name'] != '') {
         $perms[] = $args['permission_name'];
     }
     if (isset($args['edit_permission']) && $args['edit_permission'] != '') {
         $perms[] = $args['edit_permission'];
     }
     if (isset($args['ro_permission']) && $args['ro_permission'] != '') {
         $perms[] = $args['ro_permission'];
     }
     $perms += parent::get_perms($nid, $args);
     return $perms;
 }