code: def convert(self, money, to_currency, date=None):
          
          if str(money.currency) == str(to_currency):
              return copy.copy(money)
          return Money(
              amount=money.amount
              * self.rate(money.currency, to_currency, date or datetime.date.today()),
              currency=to_currency,
          )
docs: Convert the given ``money`` to ``to_currency`` using exchange rate on ``date``
  
          If ``date`` is omitted then the date given by ``money.date`` will be used.