private function normalize(string $param, string $space = '-'): string
    {
        $param = trim($param);
        if (function_exists('iconv')) {
            $param = @iconv('utf-8', 'us-ascii//TRANSLIT', $param);
        }
        $param = preg_replace('/[^a-zA-Z0-9 -]/', '', $param);
        $param = strtolower($param);
        $param = preg_replace('/[\s-]+/', $space, $param);

        return $param;
    }