code: 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)