private function requestGate(string $method, string $path, array $header = [], array $body = [], array $options = []): string
    {
        if (empty($this->accessToken)) {
            $this->renewAuthToken();
        }

        $request = new \GuzzleHttp\Psr7\Request(
            $method,
            $path,
            array_merge(
                $this->options->get('default_headers'),
                $header
            ),
            $this->createBodyForRequest(
                $this->prepareMultipartData($body)
            )
        );

        return (string) $this->sendRequest($request);
    }