Deciding inheritance at instantiation?

[Tobiah]

I have a bunch of classes from another library (the html helpers
from web2py).  There are certain methods that I'd like to add to
every one of them.  So I'd like to put those methods in a class,
and pass the parent at the time of instantiation.  Web2py has
a FORM class for instance.  I'd like to go:

	my_element = html_factory(FORM)

Then my_element would be an instance of my class, and also
a child of FORM.

I started messing with decorators, but it became difficult
for me to visualise how to do this.

Thanks!

Toby