Batch documentation snippet has an extraneous line? and broken call?

[jgeewax]

Looking at http://googlecloudplatform.github.io/gcloud-python/latest/datastore-batches.html#gcloud.datastore.batch.Batch

The last example for this method has a snippet:

>>> from gcloud import datastore
>>> dataset = datastore.get_dataset('dataset-id')
>>> with Batch() as batch:
... do_some_work(batch)
... raise Exception() # rolls back

I'm not sure why we need to have a dataset variable. I also don't know if that code even works... Might be worth chopping out? Ie, it would look like....

>>> from gcloud import datastore
>>> with datastore.Batch() as batch: # Note datastore.Batch vs Batch?
... do_some_work(batch)
... raise Exception() # rolls back

[dhermes]

I didn't realize you had filed this. #715 fixes this too.