code: private function importLibrary(string $dir): array {
          if (!isset(self::$_imported[$dir])) {
              ini_set('include_path', $dir . PATH_SEPARATOR . ini_get('include_path'));
              self::$_imported[$dir] = 1;
          }
          return self::$_imported;
      }
docs: 导入库
  @param string $dir
  @return array