bpo-16468: Clarify which objects can be passed to "choices" in argparse (GH-15566) (GH-15587)

(cherry picked from commit 84125fed2a45a9e454d7e870d8bbaf6ece3d41e8)

Co-authored-by: Raymond Hettinger <rhettinger@users.noreply.github.com>
1 file changed