What is the purpose of frozenset in Python?

FrozenSet is an immutable set, similar to set, which cannot be modified after creation.

Main uses:

• As dictionary keys: Regular sets are not hashable and cannot be used as keys. Frozenset is hashable and can be used as a key.
• Elements of another set: A regular set cannot contain another mutable set as an element. Frozenset can.
• Immutable data: If an immutable collection of unique elements is needed, frozenset guarantees that the data set will not change after creation. Useful for hash optimization and comparison.

# Example of using frozenset as a dictionary key
my_dict = {frozenset({1, 2, 3}): "value"}
print(my_dict[frozenset({1, 2, 3})])

# Example of using frozenset as an element of a set
my_set = {frozenset({1, 2}), frozenset({3, 4})}
print(my_set)