Name 'typing.io.IO' is not defined #4639
Description
The Python 3.5 docs list a typing.io something ("wrapper namespace" according to docs, class according to interpreter), which you can access with IO to get an IO type, or for example TextIO. Using this in an interpreter works fine, but mypy complains about this.
>>> typing.io.IO[str]
typing.IO[str]
>>> typing.io.TextIO
typing.TextIO[str]prettify.py:40: error: Name 'typing.io.IO' is not defined
I understand (now) that typing.IO is also possible, but the docs are very vague about that being a possibility, which is why I didn't even try it. Docs aside, since this works in the interpreter I think it should also work in mypy, which is why I'm reporting it.
