code: 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
  }
docs: // Subscribe on given channels.