def _read_data(self):
(_, _), (data_file_name, _)= self._data_file[self._version][self._segment]<EOL>with open(os.path.join(self._root, data_file_name)) as f:<EOL><INDENT>samples = json.load(f)<EOL><DEDENT>return SQuAD._get_records(samples)<EOL>
Read data.json from disk and flats it to the following format:
        Entry = (record_index, question_id, question, context, answer_list, answer_start_indices).
        Question id and list_of_answers also substituted with indices, so it could be later
        converted into nd.array

        Returns
        -------
        List[Tuple]
            Flatten list of questions