gh-125756: Document Pickler.clear_memo

[tomasr8]

Documents the public clear_memo which is currently undocumented. I think it makes to have it in the docs given that it is need when reusing Pickler objects.

The documentation is a copy of the docstring, but perhaps we could make it even clearer by replacing This method is useful when re-using picklers. with something like When reusing picklers, this method should be called after every call to dump?

• Issue: _pickle.UnpicklingError: Memo value not found at index 1 #125756

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📚 Documentation preview 📚: https://cpython-previews--125762.org.readthedocs.build/

[erik895]

I hope you fix the problems with clear_memo before making this doc public
Did you read my comment about it on the original isue?

[FFY00]

I hope you fix the problems with clear_memo before making this doc public Did you read my comment about it on the original isue?

The function is public already unfortunately, the documentation is not the source of truth, the code is.

[FFY00]

The documentation is a copy of the docstring, but perhaps we could make it even clearer by replacing This method is useful when re-using picklers. with something like When reusing picklers, this method should be called after every call to dump?

That sounds good.

We should also warn the users about potential misuse, as pointed out by @erik895