private function generateDefaultLine(array $data): string
    {
        return sprintf('    '.'<url><loc>%s</loc><lastmod>%s</lastmod><changefreq>%s</changefreq><priority>%s</priority></url>'."\n", $data['url'], date('Y-m-d', strtotime($data['lastmod'])), $data['changefreq'], $data['priority']);
    }