Value of type "stat_result" should be indexable

[Steap]

Hello,

The following code snippet works perfectly:

import stat
import os

os.stat('/tmp')[stat.ST_MODE]

But mypy returns an error:

$ mypy bug.py 
bug.py:4: error: Value of type "stat_result" is not indexable

I believe that stat_result should be indexable.

[srittau]

class stat_result is missing the __getitem__() method to implements this behaviour. Pull requests welcome!