text: const express = require('express');
  const ampify = require('ampify');
  
  const app = express();
  
  app.use(express.static('public'));
  
  app.get('/article', async (req, res) => {
    const html = `
      <html>
        <head>
          <script async src="https://www.googletagmanager.com/gtag/js?id=UA-123456789-1"></script>
          <script>
            window.dataLayer = window.dataLayer || [];
            function gtag(){dataLayer.push(arguments);}
            gtag('js', new Date());
            gtag('config', 'UA-123456789-1');
          </script>
          <title>AMP page</title>
          <link rel="stylesheet" type="text/css" href="http://localhost:5000/styles.css">
        </head>
        <body>
          <p>This is an AMP article</p>
          <div>
            <p>AMP Image</p>
            <img src="http://localhost:5000/image.png" />
          </div>
          <div>
            <p>AMP Youtube</p>
            <iframe src="http://www.youtube.com/embed/OO9oKhs80aI"
              width="560" height="315" frameborder="0" allowfullscreen>
            </iframe>
          </div>
        </body>
      </html>
    `;
  
    const amp = await ampify(html, { cwd: 'amp' });
    res.send(amp); // serving AMP content
  });
  
  app.listen(5000, () => {
    console.log('Listening on port 5000!');
  });
  