public static function comment_topic_locked($module_id, $id_in_module, $topic_identifier)
 {
     if (CommentsTopicDAO::topic_exists($module_id, $id_in_module, $topic_identifier)) {
         return CommentsTopicDAO::comments_topic_locked($module_id, $id_in_module, $topic_identifier);
     }
     return false;
 }