code: def list_ptr_records(self, device):
          
          device_type = self._resolve_device_type(device)
          href, svc_name = self._get_ptr_details(device, device_type)
          uri = "/rdns/%s?href=%s" % (svc_name, href)
          try:
              resp, resp_body = self._retry_get(uri)
          except exc.NotFound:
              return []
          records = [CloudDNSPTRRecord(rec, device)
                  for rec in resp_body.get("records", [])]
          return records
docs: Returns a list of all PTR records configured for this device.