def paid_totals_for(self, year, month):
        """
        Return paid Charges during a certain year, month with total amount,
        fee and refunded annotated.
        """
        return (
            self.during(year, month)
            .filter(paid=True)
            .aggregate(
                total_amount=models.Sum("amount"),
                total_refunded=models.Sum("amount_refunded"),
            )
        )

        Return paid Charges during a certain year, month with total amount,
        fee and refunded annotated.
        
djstripe/managers.py