In [GAE](http://code.google.com/appengine/), can you look up a [`User`](http://code.google.com/appengine/docs/python/users/userclass.html) with the User object's `user_id`?

In other words, is there something equivalent to:

```
from google.appengine.api.users import User

user = User.get_by_id(user_id)

```