time to add a __clone__ slot?
or could someone who knows what he's doing here address this comment in copy.py:
# XXX need to support copy_reg here too...
All you have to do is implement the copy protocol (ie. .copy()) for the type/class in question.
cannot find any support for that in the copy module (not in 2.0, at least)
but another reading revealed support for __copy__ and __deepcopy__ methods in at least 1.5.2 and later. intriguing...