def process_read_batch(self, batch):
        """Process a single, partitioned read.

        :type batch: mapping
        :param batch:
            one of the mappings returned from an earlier call to
            :meth:`generate_read_batches`.

        :rtype: :class:`~google.cloud.spanner_v1.streamed.StreamedResultSet`
        :returns: a result set instance which can be used to consume rows.
        """
        kwargs = copy.deepcopy(batch["read"])
        keyset_dict = kwargs.pop("keyset")
        kwargs["keyset"] = KeySet._from_dict(keyset_dict)
        return self._get_snapshot().read(partition=batch["partition"], **kwargs)