code: func MakeHub(config HubConfig) (Hub, error) {
  	if config == nil {
  		return NewHub(), nil
  	}
  
  	driverName := getDriverName(config)
  	if len(driverName) == 0 {
  		return nil, fmt.Errorf("driver name is not specified")
  	}
  	d, ok := drivers[driverName]
  	if ok {
  		h, err := d.Create(config)
  		if err != nil {
  			log.Errorf("unable to connect to %s pubsub server: %+v", driverName, err)
  			return nil, err
  		}
  		log.Info("connected to %s pubsub", driverName)
  		return h, nil
  	}
  
  	return nil, fmt.Errorf("unknown driver: %s", driverName)
  }
docs: // IMPLEMENTATION
  // MakeHub returns new instance of the pubsub hub.