docs: def save_info_df(self):
          """Saves the DataFrame with info about the runs to a JSON file"""
          logger.debug("running save_info_df")
  
          info_df = self.info_df
          top_level_dict = {'info_df': info_df, 'metadata': self._prm_packer()}
  
          # packing prms
  
          jason_string = json.dumps(top_level_dict,
                                    default=lambda info_df: json.loads(
                                        info_df.to_json()))
          with open(self.info_file, 'w') as outfile:
              outfile.write(jason_string)
          logger.info("Saved file to {}".format(self.info_file))