text: var express = require('express');
  var app = express();
  
  // set up rate limiter: maximum of five requests per minute
  var RateLimit = require('express-rate-limit');
  var limiter = new RateLimit({
    windowMs: 1*60*1000, // 1 minute
    max: 5
  });
  
  // apply rate limiter to all requests
  app.use(limiter);
  
  app.get('/:path', function(req, res) {
    let path = req.params.path;
    if (isValidPath(path))
      res.sendFile(path);
  });
  