docs: def summary_engine(**kwargs):
      """engine to extract summary data"""
      logger.debug("summary_engine")
      # farms = kwargs["farms"]
  
      farms = []
      experiments = kwargs["experiments"]
  
      for experiment in experiments:
          if experiment.selected_summaries is None:
              selected_summaries = [
                  "discharge_capacity", "charge_capacity",
                  "coulombic_efficiency",
                  "cumulated_coulombic_efficiency",
                  "ir_discharge", "ir_charge",
                  "end_voltage_discharge", "end_voltage_charge",
              ]
          else:
              selected_summaries = experiment.selected_summaries
          farm = helper.join_summaries(
              experiment.summary_frames,
              selected_summaries
          )
          farms.append(farm)
      barn = "batch_dir"
  
      return farms, barn