AttributeError: module 'mnist' has no attribute 'train_images'

[AR3342]

Hello,
I got this error: AttributeError: module 'mnist' has no attribute 'train_images'
when I ran this code:
import mnist
import itertools
import numpy as np

def prepare_data(images, labels):
images = map(lambda a: a / 255.0, map(np.asarray, map(list, map(itertools.chain.from_iterable, images))))
return list(zip(images, labels))

train = prepare_data(mnist.train_images(), mnist.train_labels())
test = prepare_data(mnist.test_images(), mnist.test_labels())

Can you please help me?