看了几遍没太懂,然后上网找了人家的解读略有开窍,连接在下面。以后想回味下,好找到路
https://zhuanlan.zhihu.com/p/21547840
https://zhuanlan.zhihu.com/p/27368456 (这个解释很不错,有点醍醐灌顶的味道)
https://www.zhihu.com/question/41979241
http://blog.csdn.net/magic_leg/article/details/73957331
http://blog.csdn.net/tayyoung/article/details/60869144
https://www.cnblogs.com/XBWer/p/4569493.html