Explanation of this Python language feature? [x for x in x for x in x] (to flatten a nested list)

[Chris Angelico]

On Sat, Apr 5, 2014 at 2:04 PM, Terry Reedy <tjreedy at udel.edu> wrote:
> I am a core developer and I am 99.99% sure that the core developers will not
> produce a CPython 2.8. For one thing we will likely do instead, see
> http://legacy.python.org/dev/peps/pep-0466/

There's also been talk of a potential compiler change for the Windows
builds, which otherwise only ever happens at minor releases. Is there
a PEP to link people to about that?

ChrisA