text: var http = require("http");
  
  http.createServer(function (req, res) {
   console.log('request received');
   // send heaader, status, and mime type
   // res.writeHead(200, {'Content-Type': 'text/html'});
   // Send the response
   res.end('Hello, Node. You requested: ' + req.url);
  }).listen(3000); // here we closed the anonymous function, then close createServer
  
  // the callback will not be called until HTTP request comes in
  // the callback doesnt block: when a request comes in, it handles, meanwhile server is just listening
  
  // log the server is running
  console.log('Server running http://127.0.0.1:3000/');
  
  
  