docs: def get_summary(self, dataset_number=None, use_dfsummary_made=False):
          """Retrieve summary returned as a pandas DataFrame."""
          dataset_number = self._validate_dataset_number(dataset_number)
          if dataset_number is None:
              self._report_empty_dataset()
              return None
  
          test = self.get_dataset(dataset_number)
  
          # This is a bit convoluted; in the old days, we used an attribute
          # called dfsummary_made,
          # that was set to True when the summary was made successfully.
          # It is most likely never
          # used anymore. And will most probably be deleted.
          if use_dfsummary_made:
              dfsummary_made = test.dfsummary_made
          else:
              dfsummary_made = True
  
          if not dfsummary_made:
              warnings.warn("Summary is not made yet")
              return None
          else:
              self.logger.info("returning datasets[test_no].dfsummary")
              return test.dfsummary