async def sum(self, columns: Union[str, List[str]]) -> Any:  # noqa: A003
        """
        Returns sum value of columns for rows matching the given criteria
        (applied with `filter` and `exclude` if set before).

        :return: sum value of columns
        :rtype: int
        """
        return await self.queryset.sum(columns=columns)

        Returns sum value of columns for rows matching the given criteria
        (applied with `filter` and `exclude` if set before).

        :return: sum value of columns
        :rtype: int
        
ormar/relations/querysetproxy.py