[Python-ideas] Optional static typing -- the crossroads

[Petr Viktorin]

On Fri, Aug 15, 2014 at 5:55 PM, Guido van Rossum <guido at python.org> wrote:
...
>> Also... Does None magically mean NoneType in type definitions?
>
> Yes.

This would mean either that `(None | None) is None`, or that (x |
None) is not always "optional x".
And if type objects grow any other common functionality, None will
have to support that as well.