Return the raw lines of the train and test files.

def _read_raw_data(path):
    """
    Return the raw lines of the train and test files.
    """

    with zipfile.ZipFile(path) as datafile:
        return (
            datafile.read("ml-100k/ua.base").decode().split("\n"),
            datafile.read("ml-100k/ua.test").decode().split("\n"),
            datafile.read("ml-100k/u.item").decode(errors="ignore").split("\n"),
            datafile.read("ml-100k/u.genre").decode(errors="ignore").split("\n"),
        )