code: func ListenAndServe(addr string, handler http.Handler) error {
  	server := NewServer(addr, handler)
  	return server.ListenAndServe()
  }
docs: /*
  ListenAndServe listens on the TCP network address addr and then calls Serve
  with handler to handle requests on incoming connections. Handler is typically
  nil, in which case the DefaultServeMux is used.
  */