code: func getVolumeFromRef(ref string) (volNamespace string, volName string, err error) {
  	refParts := strings.Split(ref, ".")
  	switch len(refParts) {
  	case 2:
  		return refParts[0], refParts[1], nil
  	case 3:
  		return refParts[1], refParts[2], nil
  	}
  	return "", "", fmt.Errorf("ref not in format volNamespace.volName or pvName.volNamespace.volName")
  }
docs: // Splits the volume ref on "." to return the volNamespace and pvName.  Neither
  // namespaces nor service names allow "." in their names.