I expect sametmax was referring to the new feature in Python 3.6 that plain old `dict` now preserves the insertion order of its elements. See docs here: https://docs.python.org/3/library/stdtypes.html#dict.values

(Or in language-lawyer terms: CPython 3.6 introduced this behavior and documented it as an implementation detail, and for Python 3.7+ it's guaranteed a feature of the language proper.)

And optional type specifiers. This was the key for me.