@steven.daprano Thanks for that information. I think that’s pretty clear. So really the question, if I want OrderedSet in python stdlib is what information needs to go into a good PEP for that feature I guess PEP 372 – Adding an ordered dictionary to collections is a good model to go after. I guess I have more thinking to do on this but welcome others’ thoughts.
By way of update, the author of the cython orderedset package responded (Interest in including OrderedSet in python standard library? · Issue #37 · simonpercivall/orderedset · GitHub) indicating that that package should not go into stdlib because it is cython based but did cast a vote for including an implementation of OrderedSet in the stdlib and that its implementation should be based on (now ordered) python dictionaries.