Missing document of WeakValueDictionary.itervaluerefs

[koyuki7w]

Documentation

WeakValueDictionary.itervaluerefs in https://github.com/python/cpython/blob/main/Lib/weakref.py#L186 has no document.

The document once existed, but removed in commit ecaab83. Perhaps the function itself should be removed.

[sobolevn]

Good find! My first thought is that we've long passed the py3 migration point, it would not be safe to remove this function. But, since it is public, tested, and semi-documented (in the source code), maybe we should instead document it again? Since I am not an expert in weakref module, this is a question for others :)

[skirpichev]

CC @freddrake

[serhiy-storchaka]

It looks that itervaluerefs() and iterkeyrefs() were planned to be renamed to valuerefs() and keyrefs(). But that change was incomplete and it was later partially reverted. We should investigate the history of these changes and find reasons for incompleting and reversion (it may be just mistake). cc @warsaw.