argparse add_argument's type should allow Callable[[AnyStr], _T]

[orinatic]

I have the following code:

    parser.add_argument("-L", "--loglevel", default="INFO",
                        type=string.upper,
                        help="Set log level output. (e.g., --log-level DEBUG)")

This fails to type-check because string.upper is Callable[[AnyStr], AnyStr], while the annotation for the type field is type: Union[Callable[[str], _T], FileType] = ....

I think it should be type: Union[Callable[[AnyStr], _T], FileType] = ...?

[srittau]

Full test case (Python 2):

import string
from argparse import ArgumentParser

parser = ArgumentParser()
parser.add_argument("-L", "--loglevel", type=string.upper)

Probably the type should be Union[Callable[[Text], _T], FileType] or even Union[Callable[[Text], _T], Callable[[str], _T], FileType]. A lone AnyStr has no meaning. Patches welcome!

[utkarsh2102]

I think that latter would make more sense (at least does to me :P).
I'll send a PR for the same.