code: func addTxtEntryToZone(zone, relative, value string, ttl int) string {
  	var zoneEntries []string
  
  	for _, line := range strings.Split(zone, "\n") {
  		zoneEntries = append(zoneEntries, fixTxtLines(line))
  	}
  
  	newZoneEntry := fmt.Sprintf("%s TXT 0 %q %d", relative, value, ttl)
  	zoneEntries = append(zoneEntries, newZoneEntry)
  
  	return strings.TrimSpace(strings.Join(zoneEntries, "\n"))
  }
docs: // addTxtEntryToZone returns DNS zone with added TXT record