https://blog.wongcw.com/2019/03/07/%e8%b0%b7%e6%ad%8c%e7%99%bc%e5%b8%83tensorflow-privacy%e2%80%8b%ef%bc%9a%e5%a4%a7%e5%b9%85%e6%8f%90%e5%8d%87ai%e6%a8%a1%e5%9e%8b%e4%b8%ad%e7%9a%84%e9%9a%b1%e7%a7%81%e4%bf%9d%e8%ad%b7/