Immutable Python classes can create a new instance on augment operations (e.g. +=)

example_augment_operations_on_immutables.py

# Class decimal.Decimal augment operations creates a new object, because it is immutable.
import decimal
a = decimal.Decimal('42')
b = decimal.Decimal('41')
b += decimal.Decimal('1')
print(a) # 42
print(b) # 42
print(a == b) # True
print(a is b) # False