code: def _next_page(self):
          
          if not self._more_results:
              return None
  
          query_pb = self._build_protobuf()
          transaction = self.client.current_transaction
          if transaction is None:
              transaction_id = None
          else:
              transaction_id = transaction.id
          read_options = helpers.get_read_options(self._eventual, transaction_id)
  
          partition_id = entity_pb2.PartitionId(
              project_id=self._query.project, namespace_id=self._query.namespace
          )
          response_pb = self.client._datastore_api.run_query(
              self._query.project, partition_id, read_options, query=query_pb
          )
          entity_pbs = self._process_query_results(response_pb)
          return page_iterator.Page(self, entity_pbs, self.item_to_value)
docs: Get the next page in the iterator.
  
          :rtype: :class:`~google.cloud.iterator.Page`
          :returns: The next page in the iterator (or :data:`None` if
                    there are no pages left).