code: func (i *Instances) ExternalID(name types.NodeName) (string, error) {
  	srv, err := getServerByName(i.compute, name)
  	if err != nil {
  		if err == ErrNotFound {
  			return "", cloudprovider.ErrInstanceNotFound
  		}
  		return "", err
  	}
  	return srv.ID, nil
  }
docs: // ExternalID returns the cloud provider ID of the specified instance (deprecated).