How to use the bigdl.dataset.base.maybe_download function in bigdl

def read_data_sets(data_dir):
    """
    Parse or download movielens 1m  data if train_dir is empty.

    :param data_dir: The directory storing the movielens data
    :return: a 2D numpy array with user index and item index in each row 
    """
    WHOLE_DATA = 'ml-1m.zip'
    local_file = base.maybe_download(WHOLE_DATA, data_dir, SOURCE_URL + WHOLE_DATA)
    zip_ref = zipfile.ZipFile(local_file, 'r')
    extracted_to = os.path.join(data_dir, "ml-1m")
    if not os.path.exists(extracted_to):
        print("Extracting %s to %s" % (local_file, data_dir))
        zip_ref.extractall(data_dir)
        zip_ref.close()
    rating_files = os.path.join(extracted_to,"ratings.dat")

    rating_list = [i.strip().split("::") for i in open(rating_files,"r").readlines()]    
    movielens_data = np.array(rating_list).astype(int)
    return movielens_data

labels is 1D unit8 nunpy array representing the label valued from 0 to 9.
    ```

    """
    TRAIN_IMAGES = 'train-images-idx3-ubyte.gz'
    TRAIN_LABELS = 'train-labels-idx1-ubyte.gz'
    TEST_IMAGES = 't10k-images-idx3-ubyte.gz'
    TEST_LABELS = 't10k-labels-idx1-ubyte.gz'

    if data_type == "train":
        local_file = base.maybe_download(TRAIN_IMAGES, train_dir,
                                         SOURCE_URL + TRAIN_IMAGES)
        with open(local_file, 'rb') as f:
            train_images = extract_images(f)

        local_file = base.maybe_download(TRAIN_LABELS, train_dir,
                                         SOURCE_URL + TRAIN_LABELS)
        with open(local_file, 'rb') as f:
            train_labels = extract_labels(f)
        return train_images, train_labels

    else:
        local_file = base.maybe_download(TEST_IMAGES, train_dir,
                                         SOURCE_URL + TEST_IMAGES)
        with open(local_file, 'rb') as f:
            test_images = extract_images(f)

        local_file = base.maybe_download(TEST_LABELS, train_dir,
                                         SOURCE_URL + TEST_LABELS)
        with open(local_file, 'rb') as f:
            test_labels = extract_labels(f)
        return test_images, test_labels

with open(local_file, 'rb') as f:
            train_images = extract_images(f)

        local_file = base.maybe_download(TRAIN_LABELS, train_dir,
                                         SOURCE_URL + TRAIN_LABELS)
        with open(local_file, 'rb') as f:
            train_labels = extract_labels(f)
        return train_images, train_labels

    else:
        local_file = base.maybe_download(TEST_IMAGES, train_dir,
                                         SOURCE_URL + TEST_IMAGES)
        with open(local_file, 'rb') as f:
            test_images = extract_images(f)

        local_file = base.maybe_download(TEST_LABELS, train_dir,
                                         SOURCE_URL + TEST_LABELS)
        with open(local_file, 'rb') as f:
            test_labels = extract_labels(f)
        return test_images, test_labels

def download_imdb(dest_dir):
    """Download pre-processed IMDB movie review data

    :argument
        dest_dir: destination directory to store the data

    :return
        The absolute path of the stored data
    """
    file_name = "imdb_full.pkl"
    file_abs_path = base.maybe_download(file_name,
                                        dest_dir,
                                        'https://s3.amazonaws.com/text-datasets/imdb_full.pkl')
    return file_abs_path

def download_glove(dest_dir):
    glove = "glove.6B.zip"
    glove_path = base.maybe_download(glove, dest_dir, GLOVE_URL)
    zip_ref = zipfile.ZipFile(glove_path, 'r')
    glove_dir = os.path.join(dest_dir, "glove.6B")
    if not os.path.exists(glove_dir):
        print("Extracting %s to %s" % (glove_path, glove_dir))
        zip_ref.extractall(glove_dir)
        zip_ref.close()

:return:

    ```
    (ndarray, ndarray) representing (features, labels)
    features is a 4D unit8 numpy array [index, y, x, depth] representing each pixel valued from 0 to 255.
    labels is 1D unit8 nunpy array representing the label valued from 0 to 9.
    ```

    """
    TRAIN_IMAGES = 'train-images-idx3-ubyte.gz'
    TRAIN_LABELS = 'train-labels-idx1-ubyte.gz'
    TEST_IMAGES = 't10k-images-idx3-ubyte.gz'
    TEST_LABELS = 't10k-labels-idx1-ubyte.gz'

    if data_type == "train":
        local_file = base.maybe_download(TRAIN_IMAGES, train_dir,
                                         SOURCE_URL + TRAIN_IMAGES)
        with open(local_file, 'rb') as f:
            train_images = extract_images(f)

        local_file = base.maybe_download(TRAIN_LABELS, train_dir,
                                         SOURCE_URL + TRAIN_LABELS)
        with open(local_file, 'rb') as f:
            train_labels = extract_labels(f)
        return train_images, train_labels

    else:
        local_file = base.maybe_download(TEST_IMAGES, train_dir,
                                         SOURCE_URL + TEST_IMAGES)
        with open(local_file, 'rb') as f:
            test_images = extract_images(f)

with open(local_file, 'rb') as f:
            train_images = extract_images(f)

        local_file = base.maybe_download(TRAIN_LABELS, train_dir,
                                         SOURCE_URL + TRAIN_LABELS)
        with open(local_file, 'rb') as f:
            train_labels = extract_labels(f)
        return train_images, train_labels

    else:
        local_file = base.maybe_download(TEST_IMAGES, train_dir,
                                         SOURCE_URL + TEST_IMAGES)
        with open(local_file, 'rb') as f:
            test_images = extract_images(f)

        local_file = base.maybe_download(TEST_LABELS, train_dir,
                                         SOURCE_URL + TEST_LABELS)
        with open(local_file, 'rb') as f:
            test_labels = extract_labels(f)
        return test_images, test_labels