'Create a batch writer object.
This method creates a context manager for writing
objects to Amazon DynamoDB in batch.
The batch writer will automatically handle buffering and sending items
in batches.  In addition, the batch writer will also automatically
handle any unprocessed items and resend them as needed.  All you need
to do is call ``put_item`` for any items you want to add, and
``delete_item`` for any items you want to delete.  In addition, you can
specify ``auto_dedup`` if the batch might contain duplicated requests
and you want this writer to handle de-dup for you.
Example usage::
with table.batch_writer() as batch:
for _ in xrange(1000000):
batch.put_item(Item={\'HashKey\': \'...\',
\'Otherstuff\': \'...\'})
# You can also delete_items in a batch.
batch.delete_item(Key={\'HashKey\': \'SomeHashKey\'})
:type overwrite_by_pkeys: list(string)
:param overwrite_by_pkeys: De-duplicate request items in buffer
if match new request item on specified primary keys. i.e
``["partition_key1", "sort_key2", "sort_key3"]``'

def batch_writer(self, overwrite_by_pkeys=None):

    return BatchWriter(self.name, self.meta.client, overwrite_by_pkeys=overwrite_by_pkeys)
