https://en.wikipedia.org/wiki/Kullback%E2%80%93Leibler_divergence
https://arxiv.org/abs/2002.07514
https://colab.research.google.com/github/https-deeplearning-ai/tensorflow-3-public/blob/main/Course%204%20-%20Generative%20Deep%20Learning/W3/ungraded_labs/C4_W3_Lab_1_VAE_MNIST.ipynb
https://colab.research.google.com/github/tensorflow/docs/blob/master/site/en/tutorials/generative/cvae.ipynb
