code: func (az *Cloud) GetZoneID(zoneLabel string) string {
  	if !az.isAvailabilityZone(zoneLabel) {
  		return ""
  	}
  
  	return strings.TrimPrefix(zoneLabel, fmt.Sprintf("%s-", az.Location))
  }
docs: // GetZoneID returns the ID of zone from node's zone label.