public static function _autoload($class_name)
 {
     if (strtolower($class_name) == 'geshi') {
         $geshi_paths = array(dirname(__FILE__) . '/geshi', HABARI_PATH . '/3rdparty/geshi', Site::get_dir('vendor') . '/geshi');
         foreach ($geshi_paths as $gp) {
             if (file_exists($gp . '/geshi.php')) {
                 self::$geshi_path = $gp;
                 require $gp . '/geshi.php';
                 return;
             }
         }
     }
 }