public static function curlExec($curlHandle)
    {
        $request = self::$requests[(int) $curlHandle];
        CurlHelper::validateCurlPOSTBody($request, $curlHandle);

        $requestCallback = self::$requestCallback;
        self::$responses[(int) $curlHandle] = $requestCallback($request);

        return CurlHelper::handleOutput(
            self::$responses[(int) $curlHandle],
            self::$curlOptions[(int) $curlHandle],
            $curlHandle
        );
    }