public function post($url, $params)
    {
        if (is_array($params)) {
            $params = $this->filterParams($params);
        }
        $this->lastRequestParams = $params;
        $this->lastRequestUrl = $this->buildUrl($url);
        return $this->curlAgent->setOption(CURLOPT_POSTFIELDS, $params)
            ->post($this->lastRequestUrl, $this->rawResponse);
    }