protected function httpRequest($url, &$content)
    {
        $client = new Client([
            'allow_redirects' => true,
            'curl' => $this->getOption('curl', []),
        ]);
        try {
            $response = $client->request('GET', $url);
        } catch (RequestException $e) {
            if ($e->hasResponse()) {
                if ($e->getResponse()->getStatusCode() == 404) {
                    throw new ImageNotFoundException(sprintf('Image Not Found : %s', $url), null, $e);
                }
            }
            if ($this->getOption('intercept_exception', false)) {
                throw new ImageNotFoundException(sprintf('Image Not Found : %s', $url), null, $e);
            } else {
                throw new ImageBackendException(sprintf("Cannot read file : %s", $url), ImageBackendException::CANNOT_READ_FILE, $e);
            }
        }
        $content = (string)($response->getBody());
        $contentType = $response->getHeader('content-type');
        return isset($contentType[0]) ? $contentType[0] : null;
    }