The data types section of the language reference (https://docs.python.org/3.10/reference/datamodel.html#the-standard-type-hierarchy) has this description directly under the Set type (which has 2 childs, set and frozenset). 

> These represent unordered, finite sets of unique, immutable objects.

I feel like this wording is a bit confusing, considering the items doesn't have to be immutable at all. Can we replace this with hashable?