if err := srv.ListenAndServe(); err != http.ErrServerClosed {
		// Error starting or closing listener:
		log.Fatalf("HTTP server ListenAndServe: %v", err)
	}

	<-idleConnsClosed
}

func ExampleListenAndServeTLS() {
	http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
		io.WriteString(w, "Hello, TLS!\n")
	})

	// One can use generate_cert.go in crypto/tls to generate cert.pem and key.pem.