code: func getDiskLUN(deviceInfo string) (int32, error) {
  	var diskLUN string
  	if len(deviceInfo) <= 2 {
  		diskLUN = deviceInfo
  	} else {
  		// extract the LUN num from a device path
  		matches := lunPathRE.FindStringSubmatch(deviceInfo)
  		if len(matches) == 2 {
  			diskLUN = matches[1]
  		} else {
  			return -1, fmt.Errorf("cannot parse deviceInfo: %s", deviceInfo)
  		}
  	}
  
  	lun, err := strconv.Atoi(diskLUN)
  	if err != nil {
  		return -1, err
  	}
  	return int32(lun), nil
  }
docs: // getDiskLUN : deviceInfo could be a LUN number or a device path, e.g. /dev/disk/azure/scsi1/lun2