code: def sum(self):
          
          return GroupedDataFrameWeld(
              grizzly_impl.groupby_sum(
                  self.columns,
                  self.column_types,
                  self.grouping_columns,
                  self.grouping_column_types
              ),
              self.grouping_column_names,
              self.column_names,
              self.grouping_column_types,
              self.column_types
          )
docs: Summary
  
          Returns:
              TYPE: Description