Where's UserList.ListMixin?

[Matthew Barnes]

This may be a naive question, but since Python 2.3 added a handy
little DictMixin class to its UserDict module it seems to me like
UserList.ListMixin and maybe even UserString.StringMixin should have
followed (although I'm not sure how useful a StringMixin class would
really be).

I'm just curious.  Is there a reason these classes weren't included? 
Is anybody looking into this for Python 2.4?  Should I submit a patch?

Matthew Barnes