If we need a place to name types that don't deserve being builtins, perhaps new.py is a better place?
The new. prefix is natural enough for
m = new.module('name')
type but it looks pretty awkward in
if isinstance(obj, new.generator):
What's the meaning of 'new' in this context?
Sometimes you ask too many questions. :-)
Let's just say that this is a historically available name. I don't expect that isinstance(obj, generator) is a very common question to ask, so I don't mind if you have to ask it in a somewhat awkward way.
The idea of using the types module turned out to have more problems than appeared at first but new doesn't look much better to me.
Using new.py looks much better to me because it already works.
--Guido van Rossum (home page: http://www.python.org/%7Eguido/)