code: func (az *Cloud) getVmssMachineID(resourceGroup, scaleSetName, instanceID string) string {
  	return fmt.Sprintf(
  		vmssMachineIDTemplate,
  		az.SubscriptionID,
  		strings.ToLower(resourceGroup),
  		scaleSetName,
  		instanceID)
  }
docs: // getVmssMachineID returns the full identifier of a vmss virtual machine.