built-in-methods.py

class Currency:
    def __init__(self, code, exchange_to_usd):
        self.amount = 0.00
        self.code = code
        self.exchange_to_usd = exchange_to_usd

    def set_amount(self, amount):
        self.amount = amount

    def in_currency(self, amount):
        return amount / self.exchange_to_usd

    def to_usd(self, amount=None):
        to_convert = amount or self.amount
        return to_convert * self.exchange_to_usd

    def __eq__(self, other):
        # Exactly equal, ==
        return self.to_usd() == other.to_usd()

    def __gt__(self, other):
        # Greater than, >
        return self.to_usd() > other.to_usd()

    def __lt__(self, other):
        # Less than, <
        pass

    def __le__(self, other):
        # Less than or equal to, <=
        pass

    def __ge__(self, other):
        # Greater than or equal to, >=
        pass


pounds = Currency("GBP", 1.21)
pounds.set_amount(1000)
euros = Currency("EUR", 1.07)
euros.set_amount(1000)

print(pounds > euros)