code: func (c *Client) FindTxtRecord(zoneName, fqdn string) (*TXTRecord, error) {
  	host := dns01.UnFqdn(strings.TrimSuffix(dns01.UnFqdn(fqdn), zoneName))
  
  	reqURL := *c.BaseURL
  	reqURL.Path += "records.json"
  
  	q := reqURL.Query()
  	q.Add("domain-name", zoneName)
  	q.Add("host", host)
  	q.Add("type", "TXT")
  	reqURL.RawQuery = q.Encode()
  
  	result, err := c.doRequest(http.MethodGet, &reqURL)
  	if err != nil {
  		return nil, err
  	}
  
  	// the API returns [] when there is no records.
  	if string(result) == "[]" {
  		return nil, nil
  	}
  
  	var records TXTRecords
  	if err = json.Unmarshal(result, &records); err != nil {
  		return nil, fmt.Errorf("TXT record unmarshaling error: %v: %s", err, string(result))
  	}
  
  	for _, record := range records {
  		if record.Host == host && record.Type == "TXT" {
  			return &record, nil
  		}
  	}
  
  	return nil, nil
  }
docs: // FindTxtRecord return the TXT record a zone ID and a FQDN