[$] An ordered set for Python?

Python has lots of different options for mutable data structures, bothdirectly in the language and in the standard library. Lists, dictionaries (or "dicts"), andsets are the foundation, but two of those maintain an order based on howthe elements are added, while sets do not. A recent discussion on the Python Discourse forum raised theidea of adding an ordered variant of sets; while it does not look likethere is a big push to add the feature, the discussion did show some ofwhat is generally needed to get new things into the language-and could welllead to its inclusion.