code: func rcodezeroChangesByZone(zones []*rc0.Zone, changeSet []*rc0.RRSetChange) map[string][]*rc0.RRSetChange {
  
  	changes := make(map[string][]*rc0.RRSetChange)
  	zoneNameIDMapper := zoneIDName{}
  	for _, z := range zones {
  		zoneNameIDMapper.Add(z.Domain, z.Domain)
  		changes[z.Domain] = []*rc0.RRSetChange{}
  	}
  
  	for _, c := range changeSet {
  		zone, _ := zoneNameIDMapper.FindZone(c.Name)
  		if zone == "" {
  			log.Debugf("Skipping record %s because no hosted zone matching record DNS Name was detected ", c.Name)
  			continue
  		}
  		changes[zone] = append(changes[zone], c)
  	}
  
  	return changes
  }
docs: // Helper function