docs: def get_ocv_old(self, cycle_number=None, ocv_type='ocv', dataset_number=None):
          """Find ocv data in DataSet (voltage vs time).
  
          Args:
              cycle_number (int): find for all cycles if None.
              ocv_type ("ocv", "ocvrlx_up", "ocvrlx_down"):
                       ocv - get up and down (default)
                       ocvrlx_up - get up
                       ocvrlx_down - get down
              dataset_number (int): test number (default first)
                  (usually not used).
          Returns:
                  if cycle_number is not None
                      ocv or [ocv_up, ocv_down]
                      ocv (and ocv_up and ocv_down) are list
                      containg [time,voltage] (that are Series)
  
                  if cycle_number is None
                      [ocv1,ocv2,...ocvN,...] N = cycle
                      ocvN = pandas DataFrame containing the columns
                      cycle inded, step time, step index, data point, datetime,
                          voltage
                      (TODO: check if copy or reference of dfdata is returned)
          """
          # function for getting ocv curves
          dataset_number = self._validate_dataset_number(dataset_number)
          if dataset_number is None:
              self._report_empty_dataset()
              return
          if ocv_type in ['ocvrlx_up', 'ocvrlx_down']:
              ocv = self._get_ocv(dataset_number=None,
                                  ocv_type=ocv_type,
                                  select_last=True,
                                  select_columns=True,
                                  cycle_number=cycle_number,
                                  )
              return ocv
          else:
              ocv_up = self._get_ocv(dataset_number=None,
                                     ocv_type='ocvrlx_up',
                                     select_last=True,
                                     select_columns=True,
                                     cycle_number=cycle_number,
                                     )
              ocv_down = self._get_ocv(dataset_number=None,
                                       ocv_type='ocvrlx_down',
                                       select_last=True,
                                       select_columns=True,
                                       cycle_number=cycle_number,
                                       )
              return ocv_up, ocv_down