def create(kls, url, strict=True):
        """ factory of App

        :param str url: url of path of Swagger API definition
        :param bool strict: when in strict mode, exception would be raised if not valid.
        :return: the created App object
        :rtype: App
        :raises ValueError: if url is wrong
        :raises NotImplementedError: the swagger version is not supported.
        """
        app = kls.load(url)
        app.prepare(strict=strict)

        return app
factory of App

        :param str url: url of path of Swagger API definition
        :param bool strict: when in strict mode, exception would be raised if not valid.
        :return: the created App object
        :rtype: App
        :raises ValueError: if url is wrong
        :raises NotImplementedError: the swagger version is not supported.