If you need just a single method once, don't use a mixin; just do B.meth = A.meth.im_func. Do not underestimate the burden of mixins on people reading your code (at least, for me it is burden, since I have to draw the inheritance tree in my mind, look at which methods are involved, wonder about the resolution order etc.)
Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list