docs: def get_number_of_cycles(self, dataset_number=None, steptable=None):
          """Get the number of cycles in the test."""
          if steptable is None:
              dataset_number = self._validate_dataset_number(dataset_number)
              if dataset_number is None:
                  self._report_empty_dataset()
                  return
              d = self.datasets[dataset_number].dfdata
              no_cycles = np.amax(d[self.headers_normal.cycle_index_txt])
          else:
              no_cycles = np.amax(steptable[self.headers_step_table.cycle])
          return no_cycles