Wing vendored typing/typing_extensions
src/typing.py: CPython 3.14 stdlib (bundled runtime)
typing_extensions/src_py3/typing_extensions.py: python/typing_extensions commit 83400e979b8e3b0b647f9a6a57f0275230e5f19f
python2/ and src_py2/ from the legacy python/typing repo were dropped along
with the rest of Python 2 stub support (Wing 12 soft-drops Python 2, and
modern typeshed has no py2 stubs).
