Imports the batch of outgoing transactions into
        model IncomingTransaction.

def import_batch(self, filename):
        """Imports the batch of outgoing transactions into
        model IncomingTransaction.
        """
        batch = self.batch_cls()
        json_file = self.json_file_cls(name=filename, path=self.path)
        try:
            deserialized_txs = json_file.deserialized_objects
        except JSONFileError as e:
            raise TransactionImporterError(e) from e
        try:
            batch.populate(deserialized_txs=deserialized_txs, filename=json_file.name)
        except (
            BatchDeserializationError,
            InvalidBatchSequence,
            BatchAlreadyProcessed,
        ) as e:
            raise TransactionImporterError(e) from e
        batch.save()
        batch.update_history()
        return batch