Python Set Types:

A set type is a collection data type that supports the membership operator (in), the size function (len()), and is iterable. In addition, set types at least provide a set.isdisjoint() method, and support for comparisons, as well as support for the bitwise operators (which in the context of sets are used for union, intersection, etc.).

Python provides two built-in set types: the mutable set type and the immutable frozenset.

When iterated, set types provide their items in an arbitrary order.