old_contents: //server.js
  var http = require('http');
  handler=function(req,res){
      makeHTTPRequest(req,res);
  }
  
  function makeHTTPRequest(request,response) {
      var proxy=http.request(request.headers.host);
  
      response.writeHead(200);
      response.end('HI');
  }
  
  http.createServer(handler).listen(process.env.PORT);
new_contents: var PORT=Number(process.env.PORT || 3000);
  
  var http = require('http');
  handler=function(req,res){
      makeHTTPRequest(req,res);
  }
  
  function makeHTTPRequest(request,response) {
      var proxy=http.request(request.headers.host);
  
      response.writeHead(200);
      response.end('HI');
  }
  
  http.createServer(handler).listen(PORT);
subject: fix port