[web2py] Can't use custom classes in cache

[Michael Toomim]

Hi all, it appears I can't use any of my own classes in the cache:

   class Blah:
       pass

   b = blah()
   cache.disk('blah', lambda: b)

This results in:

   AttributeError: 'module' object has no attribute 'Blah'

I think this is because the things I'm defining (e.g. in models/)
isn't accessible from cache.py in gluon/. Is there a way around this?