private function cleanURL(string $url = '')
    {
        $url = str_replace(' ', '-', $url); 				// Replaces all spaces with hyphens
        $url = preg_replace('/[^A-Za-z0-9\/\-]+/', '-', $url);	// Replaces special characters with hyphens

        // remove "/" prefix on generated URL
        if (substr($url, 0, 1) == '/') {
            return preg_replace('/\//', '', $url, 1);
        }

        return $url;
    }