static public function getFullUrl($url, $ep = null)
    {
        ApiDebug::p('create full url, based on global constant');

        $name = ($ep)
            ? 'UPWORK_BASE_URL_' . strtoupper($ep)
            : 'UPWORK_BASE_URL';

        $fullUrl = constant($name) . $url;
        ApiDebug::p('url', $fullUrl);

        return $fullUrl;
    }