protected function commitPart($part)
    {
        $commit_url = FilestackConfig::UPLOAD_URL . '/multipart/commit';
        $commit_data = $this->buildCommitData($part);

        $response = $this->sendRequest('POST', $commit_url,
                                       ['multipart' => $commit_data]);

        $status_code = $response->getStatusCode();
        if ($status_code !== 200) {
            throw new FilestackException($response->getBody(),
                $status_code);
        }
        return $status_code;
    }