On Mon, Aug 4, 2014 at 12:57 PM, Ethan Furman <ethan@stoneleaf.us> wrote:
'allow_none' is definitely clearer.

I disagree. Unlike "nullable", "allow_none" does not tell me what happens on the C side when I pass in None.  If the receiving type is PyObject*, either NULL or Py_None is a valid choice.