[Firestore] WriteBatch doesn't return instance so you cannot chain.

[crwilcox]

The WriteBatch methods don’t return the WriteBatch instances for chaining.

[tseaver]

We pretty much never do chaining in Python libs.

[tseaver]

I would suggest that the "Pythonic" way to provide multiple operations would be to make WriteBatch a context manager, invoking commit from within its __exit__. E.g.:

with client.batch() as batch:
    batch.create(client.document('documents', 'foo'), {...})
    batch.set(client.document('documents, 'bar'), {...}, merge=True)
    batch.delete(client.document('documents, 'baz'))

I'm surprised that it doesn't already operate this way.