code: func extractResourceGroupByVMSSNicID(nicID string) (string, error) {
  	matches := vmssIPConfigurationRE.FindStringSubmatch(nicID)
  	if len(matches) != 4 {
  		return "", fmt.Errorf("error of extracting resourceGroup from nicID %q", nicID)
  	}
  
  	return matches[1], nil
  }
docs: // extractResourceGroupByVMSSNicID extracts the resource group name by vmss nicID.