init.go
func Subscribe(channels []string) (Channel, error) {
	if hubInstance == nil {
		return nil, errorNohub
	}
	r, err := hubInstance.Subscribe(channels)
	if err != nil {
		log.Errorf("pubsub subscribe failed: %+v", err)
		return nil, err
	}
	log.Debug("subscibe to %v", channels)
	return r, nil
}
func Subscribe(channels []string) (Channel, error) {
	if hubInstance == nil {
		return nil, errorNohub
	}
	r, err := hubInstance.Subscribe(channels)
	if err != nil {
		log.Errorf("pubsub subscribe failed: %+v", err)
		return nil, err
	}
	log.Debug("subscibe to %v", channels)
	return r, nil
}
// Subscribe on given channels.