def METHOD_NAME(self, index: int) -> xr.Dataset:
    """Get or compute the dataset for the level at given *index*.
    :param index: the level index
    :return: the dataset for the level at *index*.
    """
    if index not in self._level_datasets:
        with self._lock:
            # noinspection PyTypeChecker
            level_dataset = self._get_dataset_lazily(index,
                                                     self._parameters)
            self.set_dataset(index, level_dataset)
    # noinspection PyTypeChecker
    return self._level_datasets[index]