参考：
https://www.jianshu.com/p/bfd0148b292e
https://blog.csdn.net/weixin_43948816/article/details/86063235
https://www.jianshu.com/p/3d0bb34c488a
源码：
https://github.com/google-research/bert
参考：
https://www.jianshu.com/p/d7ce41b58801
https://blog.csdn.net/jiaowoshouzi/article/details/89388794
原文：https://www.cnblogs.com/sybil-hxl/p/12624057.html