nats/driver.go
func Open(URL ...string) (pubsub.Hub, error) {
	if len(URL) == 0 {
		URL = []string{nats.DefaultURL}
	}

	log.Info("connecting to nats hub: %v", URL)

	conn, err := nats.Connect(URL[0])
	if err != nil {
		return nil, err
	}

	return &hub{
		conn: conn,
		subs: make(map[*sub]struct{}),
	}, nil
}
func Open(URL ...string) (pubsub.Hub, error) {
	if len(URL) == 0 {
		URL = []string{nats.DefaultURL}
	}

	log.Info("connecting to nats hub: %v", URL)

	conn, err := nats.Connect(URL[0])
	if err != nil {
		return nil, err
	}

	return &hub{
		conn: conn,
		subs: make(map[*sub]struct{}),
	}, nil
}
// Open creates pubsub hub connected to nats server.