def charges_net_effect(self):
        """
        The total effect of the net_affecting charges (note affect vs effect here).

        Currently this is single currency only (AMAAS-110).

        Cast to Decimal in case the result is zero (no net_affecting charges).

        :return:
        """
        return Decimal(sum([charge.charge_value for charge in self.charges.values()
                            if charge.net_affecting]))