code: func (c *PDNSAPIClient) ListZones() (zones []pgo.Zone, resp *http.Response, err error) {
  	for i := 0; i < retryLimit; i++ {
  		zones, resp, err = c.client.ZonesApi.ListZones(c.authCtx, defaultServerID)
  		if err != nil {
  			log.Debugf("Unable to fetch zones %v", err)
  			log.Debugf("Retrying ListZones() ... %d", i)
  			time.Sleep(retryAfterTime * (1 << uint(i)))
  			continue
  		}
  		return zones, resp, err
  	}
  
  	log.Errorf("Unable to fetch zones. %v", err)
  	return zones, resp, err
  
  }
docs: // ListZones : Method returns all enabled zones from PowerDNS
  // ref: https://doc.powerdns.com/authoritative/http-api/zone.html#get--servers-server_id-zones