http://deeplearning.cs.cmu.edu/recitations/rec8.attention.pdf
https://github.com/cmudeeplearning11785/deep-learning-tutorials/blob/master/recitation-8/numbers_colors.ipynb
CMU Deep Learning 2018 by Bhiksha Raj 学习记录(20) Recitation 8: Attention
原文：https://www.cnblogs.com/ecoflex/p/8970891.html