```coffeescript
app = require('express')()

app.get '/', (req, res) ->
  res.send 'Hello World!'
  console.log 'GET /'

app.listen(3000)
```

Fix listening port for production
user
```coffeescript
app = require('express')()

app.get '/', (req, res) ->
  res.send 'Hello World!'
  console.log 'GET /'

port = process.env.PORT || 3000

app.listen(port)
```
assistant