ENH: vendor typing_extensions

[jbrockmendel]

• closes ENH: Vendor typing_extensions #34869
• tests added / passed
• passes black pandas
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

haven't figured out how to make isort and black ignore this file

[pep8speaks]

Hello @jbrockmendel! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file pandas/_vendored/typing_extensions.py:

Line 1985:89: E501 line too long (98 > 88 characters)

Comment last updated at 2020-09-01 16:25:26 UTC

[jbrockmendel]

cc @WillAyd @simonjayhawkins thoughts on getting this to pass checks?

[WillAyd]

FWIW I think OK to run the new module through isort / black; doesn't need to be a perfect reproduction

AFAICT code check failures are mostly around internal style rules we place; OK to update to those as well as they are mostly cosmetic

[simonjayhawkins]

Thanks @jbrockmendel

do we need any sort of testing for this?

[WillAyd]

Is this still required to ignore?

[jbrockmendel]

either way i guess

[WillAyd]

Let's remove if not necessary; less things to ponder is always better

[jbrockmendel]

do we need any sort of testing for this?

I wouldn't bother. FWIW not needing to worry about that is part of why i suggested making this a dependency in #34869

[jreback]

thanks @jbrockmendel