docs: def load_info_df(self, file_name=None):
          """Loads a DataFrame with all the needed info about the run
          (JSON file)"""
  
          if file_name is None:
              file_name = self.info_file
  
          with open(file_name, 'r') as infile:
              top_level_dict = json.load(infile)
  
          new_info_df_dict = top_level_dict['info_df']
          new_info_df = pd.DataFrame(new_info_df_dict)
          self.info_df = new_info_df
  
          self._prm_packer(top_level_dict['metadata'])
          self.info_file = file_name
          logger.debug("loaded info_df")
          logger.debug(" info_file: %s" % self.info_file)