[
        // put any GuzzleHttp options here
    ]
];
try {
    $parser = new SitemapParser('MyCustomUserAgent', $config);
    $parser->parse('https://www.google.com/robots.txt');
    foreach ($parser->getSitemaps() as $url => $tags) {
        echo 'Sitemap
';
        echo 'URL: ' . $url . '
';
        echo 'LastMod: ' . $tags['lastmod'] . '
';
        echo '