Ordering python sets

[Mr.SpOOn]

The discussion's gone a bit off topic so I don't know if it is a good
idea to continue here. I'll try.

My first question was about a way to order a python set. Someone
suggested to try this module:

http://code.activestate.com/recipes/528878/

It seemed pretty good, but I've tried it just today and something doesn't work.
I think it doesn't work because what I have to order are objects and
not just numbers. Anyway, I'm not sure that this is the problem.

What I get when I try to append one of my object is:

  File "notes.py", line 245, in __init__
    self.append(root)
  File "ordered_set.py", line 78, in append
    self._insertatnode(self._end.prev, element)
  File "ordered_set.py", line 110, in _insertatnode
    if element in self._map:
TypeError: unhashable instance

Don't know if it is important, but inside the class of the object that
I'm trying to append, I redefined the __eq__ and __gt__ method.