Why do I need to do 2 imports for datastore transactions?

What I see in the docs:

``` python
>>> from gcloud import datastore
>>> from gcloud.datastore.transaction import Transaction
>>> datastore.set_defaults()
>>> with Transaction():
...     datastore.put([entity1, entity2])
```

What I want to do:

``` python
>>> from gcloud import datastore
>>> with datastore.Transaction() as t:
...     t.put([entity1, entity2])
```
