Sets are unordered collections of unique objects, there are two types of set :
Sets - They are mutable and new elements can be added once sets are defined
basket = {'apple', 'orange', 'apple', 'pear', 'orange', 'banana'}
print(basket) # duplicates will be removed
> {'orange', 'banana', 'pear', 'apple'}
a = set('abracadabra')
print(a) # unique letters in a
> {'a', 'r', 'b', 'c', 'd'}
a.add('z')
print(a)
> {'a', 'c', 'r', 'b', 'z', 'd'}
Frozen Sets - They are immutable and new elements cannot added after its defined.
b = frozenset('asdfagsa')
print(b)
> frozenset({'f', 'g', 'd', 'a', 's'})
cities = frozenset(["Frankfurt", "Basel","Freiburg"])
print(cities)
> frozenset({'Frankfurt', 'Basel', 'Freiburg'})