Python DDD - Value Object idea. Immutable attributes, methods, structural equality.

money.py

from collections import namedtuple

class Money(namedtuple('Money', ['amount', 'currency'])):
    def add(self, amount):
        return Money(self.amount + amount, self.currency)

m = Money(20, 'USD')
print(m)
# Money(amount=20, currency='USD')

m.add(10)
# Money(amount=30, currency='USD')

m1 = Money(20, 'USD')
m2 = Money(20, 'PLN')

m1 == m
# True

m1 == m2
# False