docs: def read_folder(folder):
      """
      Parameters
      ----------
      folder : str
  
      Returns
      -------
      list of HandwrittenData objects
      """
      hwr_objects = []
      for filepath in natsort.natsorted(glob.glob("%s/*.inkml" % folder)):
          tmp = inkml.read(filepath)
          for hwr in tmp.to_single_symbol_list():
              hwr_objects.append(hwr)
      logging.info("Done reading formulas")
      save_raw_pickle(hwr_objects)
      return hwr_objects