code: func extractScaleSetNameByProviderID(providerID string) (string, error) {
  	matches := scaleSetNameRE.FindStringSubmatch(providerID)
  	if len(matches) != 2 {
  		return "", ErrorNotVmssInstance
  	}
  
  	return matches[1], nil
  }
docs: // extractScaleSetNameByProviderID extracts the scaleset name by vmss node's ProviderID.