assert & log
http://www.cnblogs.com/ajianbeyourself/p/3813257.htmlDjango model manager
http://blog.csdn.net/sundaydashu/article/details/7959977Django import(name, fromlist=([],))
https://stackoverflow.com/questions/2724260/why-does-pythons-import-require-fromlist-
Django 使用Max(list)提示如下，原因是list中存在None，需要处理
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bootstrap 动态限定起止时间
http://blog.csdn.net/wzj2584454/article/details/67636241
