protected function makeAbsoluteUrl($relativeUrl, $baseUrl = null)
    {
        $baseUrl = $baseUrl ?: $this->baseUrl;
        if (empty($baseUrl)) {
            throw new \RuntimeException('No base URL');
        }
        $base = \GuzzleHttp\Psr7\uri_for($baseUrl);

        return $base->withPath($relativeUrl)->__toString();
    }