public function post($data, $uri = null, $remainingRedirects = null,
            $contentType = null, $extraHeaders = null)
    {
        $requestData = $this->prepareRequest(
            'POST', $uri, $extraHeaders, $data, $contentType);
        return $this->performHttpRequest(
                $requestData['method'], $requestData['url'],
                $requestData['headers'], $requestData['data'],
                $requestData['contentType']);
    }