https://www.leiphone.com/news/201611/oykRjZskXc2kByKx.html https://www.zhihu.com/question/38102762/answer/85238569 https://blog.youkuaiyun.com/leayc/article/details/77645877 BNLSTM实现代码: https://github.com/OlavHN/bnlstm