def get_next_batch(self):
        """
        This method is called from the manager. It must return a list or a generator
        of BaseRecord objects.
        When it has nothing else to read, it must set class variable "finished" to True.
        """
        if self.iterator is None:
            self.iterator = self.iteritems()

        count = 0
        while count < self.batch_size:
            count += 1
            yield next(self.iterator)
        self.logger.debug('Done reading batch')