Takes a a url string, http.Server, a request handling function, or an object that implements an app.listen() method (which mirrors the http.serve interface).

Accepts an optional second argument of secure to determine whether connections should be over HTTPS (true) or HTTP (false)

If SuperDeno identifies that a server is not already listening for connections, then one is bound to an ephemeral port for you so there is no need to keep track of ports.