[Zope] Changing owner of a folder object

[Jeff Gentry]

If I add a folder in my python code as follows (where users is where I
wish to create this folder and username is to be the name of the folder):

manage_addFolder(users, username, username)

How do I go about changing the owner of that folder (to the user named by
the 'username' variable)?

If 'uF' is a handle to the folder object created above, the method:

uF.changeOwnership(username)

fails.  It appears that changeOwnership() expects an actual user object
and not the character string.  I then tried using the 'getUser()' method
to retrieve the user object associated w/ the name but keep getting
NotImplentedErrors.  

Clearly I'm doing something pretty wrong here - the newest documentation I
can find on the subject is the developers guide for Zope 2.4, which
perhaps is out of date?

Thanks
-J