I think you've installed one twitter package, and look at another documentation. Ie: python-1.7.2 is the project from https://github.com/sixohsix/twitter, while you're looking at the http://code.google.com/p/python-twitter/ documentation. No match between both :)
So for the one you've installed, if you check the source code, a stream example is available, and other various examples in the pydoc:
from twitter import Twitter # ... twitter = Twitter( auth=OAuth(token, token_key, con_secret, con_secret_key))) # Get the public timeline twitter.statuses.public_timeline()