Return the raw lines of the train and test files.

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

    path = _get_movielens_path()

    if not os.path.isfile(path):
        _download_movielens(path)

    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'))