code: protected static function create(string $app) {
          if (self::$_status > self::_STATUS_INITIAL) {
              Console::warning('Cannot create application once the service is started.');
              return;
          }
          if (isset(self::$_apps[$app]))
              Console::fatal("Failed to create app. App \"$app\" exists!");
      }
docs: 注册服务
  
  @param string $app