tf.contrib.learn.preprocessing will be deprecated

[EtoDemerzel0427]

since tf.contrib.learn.preprocessing will be deprecated in future version of TensorFlow, the code in chapter 7 about the bag-of-word should be updated by using tf.data or something else.

[nfmcclure]

Thanks @EtoDemerzel0427 for bringing this up. I'll see what I can do.

[Cumberbatch08]

who can give me a example?