code: def to(self, currency):
          
          if currency == self._currency:
              return self
          rate = xrates.quotation(self._currency, currency)
          if rate is None:
              raise ExchangeRateNotFound(xrates.backend_name,
                                           self._currency, currency)
          amount = self._amount * rate
          return self.__class__(amount, currency)
docs: Return equivalent money object in another currency