def sort_values(self, ascending=False):
        if self.index_type is not None:
            index_expr = grizzly_impl.get_field(self.expr, 0)
            column_expr = grizzly_impl.get_field(self.expr, 1)
            zip_expr = grizzly_impl.zip_columns([index_expr, column_expr])
            result_expr = grizzly_impl.sort(zip_expr, 1, self.weld_type, ascending)
            unzip_expr = grizzly_impl.unzip_columns(
                result_expr,
                [self.index_type, self.weld_type]
            )
            return SeriesWeld(
                unzip_expr,
                self.weld_type,
                self.df,
                self.column_name,
                self.index_type,
                self.index_name
            )
        else:
            result_expr = grizzly_impl.sort(self.expr)