private function extractXml($response)
    {
        /**
         * Ugly way of seeing if an attachment is present in the response.
         */
        if (strpos($response, 'application/xop+xml') === false) {
            return array($response, array('data' => null, 'mimeType' => null));
        } else {
            return $this->extractXmlAndAttachment($response);
        }
    }