Make a BatchWriteItem call to Dynamo

def _batch_write_item(self, items):
        """ Make a BatchWriteItem call to Dynamo """
        kwargs = {
            'RequestItems': {
                self.tablename: items,
            },
            'ReturnConsumedCapacity': self.return_capacity,
            'ReturnItemCollectionMetrics': self.return_item_collection_metrics,
        }
        return self.connection.call('batch_write_item', **kwargs)