docs: def _get_data_from_rawfile(path_to_data, raw_data_id):
      """Get a HandwrittenData object that has ``raw_data_id`` from a pickle file
         ``path_to_data``.
         :returns: The HandwrittenData object if ``raw_data_id`` is in
                   path_to_data, otherwise ``None``."""
      loaded = pickle.load(open(path_to_data, "rb"))
      raw_datasets = loaded['handwriting_datasets']
      for raw_dataset in raw_datasets:
          if raw_dataset['handwriting'].raw_data_id == raw_data_id:
              return raw_dataset['handwriting']
      return None