def save(self, filename=None):
        filename = Path(filename) if filename is not None else self.filename
        with filename.open("w") as f:
            f.write(self.yaml)
def _file_name_to_batch_number(example_file_name):
    """Parses batch number from file.

    :param example_file_name: See doc for `find_example_file`.
    :return: batch_number: Integer.
    :raises: ValueError: if batch number cannot be parsed from file name.
    """

    pathless_file_name = os.path.split(example_file_name)[-1]
    extensionless_file_name = os.path.splitext(pathless_file_name)[0]
    return int(extensionless_file_name.split('input_examples_batch')[-1])