text: var express = require('express');
  var serveStatic = require('serve-static');
  
  var app = express();
  app.use(serveStatic(__dirname + '/public', {
    setHeaders: (res, path) => {
      res.setHeader('Cache-Control', 'no-cache, no-store, must-revalidate');
    }
  }));
  
  var port = process.env.port || 3000;
  app.listen(port, function () {
    console.log('Listening on http://localhost:' + port);
  });