[Python-ideas] make __closure__ writable

[Yury Selivanov]

Can we make the __closure__ attribute writeable?  Since __code__ already is,
and it is possible to tackle with the opcodes, having no way of rewriting 
__closure__ (except creating a completely new function) is annoying.

I don't think it will somehow harm python, as those who want to break it can
do it already in multiple ways, easier than playing with __closure__.

-
Yury