code: func (i *Instances) InstanceID(ctx context.Context, name types.NodeName) (string, error) {
  	srv, err := getServerByName(i.compute, name)
  	if err != nil {
  		if err == ErrNotFound {
  			return "", cloudprovider.InstanceNotFound
  		}
  		return "", err
  	}
  	// In the future it is possible to also return an endpoint as:
  	// <endpoint>/<instanceid>
  	return "/" + srv.ID, nil
  }
docs: // InstanceID returns the cloud provider ID of the specified instance.