[issue45519] Minor docstring improvement in __contains__

[Ivan Savov]

Change by Ivan Savov <ivan.savov at gmail.com>:


----------
keywords: +patch
pull_requests: +27314
stage:  -> patch review
pull_request: https://github.com/python/cpython/pull/29043

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue45519>
_______________________________________