[docs] [issue27618] docs for threading.Lock claim it's a class (since 3.3), but it's not (and has never been, apparently)

[Mariatta Wijaya]

Mariatta Wijaya added the comment:

Thanks for the PR Cheryl. 

You can backport using cherry_picker.py 
Note that there's a recent update to it: https://github.com/python/core-workflow/tree/master/cherry_picker

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stage: patch review -> backport needed

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