code: def _get_related_exporter(self, related_obj, column):
          
          result = column.get('sqla_ods_exporter')
          if result is None:
              result = column['sqla_ods_exporter'] = SqlaOdsExporter(
                  related_obj.__class__,
                  is_root=False,
                  title=column.get('label', column['key']),
              )
              self.add_sheet(result)
          return result
docs: returns an SqlaOdsExporter for the given related object and stores it in
          the column object as a cache