NoneType and new instances

[Terry Reedy]

Ethan's proposal was accepted on python-ideas. In Python 3.3, the 
classes for the singletons None, Ellipsis, and NotImplemented will be 
callables that return the singleton.

It turns out that the reason an exception is now raised is that there 
currently is no .__new__ method, so an exception is raised by default. 
.__new__ methods returning the singleton have been added.

Terry Jan Reedy