private function removeTrailingSlash($url)
    {
        // if there is a final slash, we take the URL without this slash (expected URL format)
        if (strlen($url) > 5
            && $url[strlen($url) - 1] == '/'
        ) {
            $url = substr($url, 0, strlen($url) - 1);
        }

        return $url;
    }