frozenset

sets sind veränderliche Objekte und frozensets sind unveränderlich (immutable)

e.g.

>>> x = frozenset(["a","b","c"])

>>> y = frozenset(["c", "d","e"])

>>> x | y

frozenset(['a', 'c', 'b', 'e', 'd'])

>>> x & y

frozenset(['c'])

>>>