Calls import_batch for the next filename in the queue
        and "archives" the file.

        The archive folder is typically the folder for the deserializer queue.

def next_task(self, item, **kwargs):
        """Calls import_batch for the next filename in the queue
        and "archives" the file.

        The archive folder is typically the folder for the deserializer queue.
        """
        filename = os.path.basename(item)
        try:
            self.tx_importer.import_batch(filename=filename)
        except TransactionImporterError as e:
            raise TransactionsFileQueueError(e) from e
        else:
            self.archive(filename)