[python] " and or "

Python笔记之and or陷阱 - 未知世界 - ITeye技术网站
http://calmness.iteye.com/blog/227020
Python三目运算，and or陷阱_土拨先生_百度空间
http://hi.baidu.com/tuuboo/blog/item/0945d3fc2c4fbe43d6887dbb.html
[python] and or 表达式陷阱一则。 - cpunion - 博客园
http://www.cnblogs.com/cpunion/archive/2005/08/01/204597.html
4.6. The Peculiar Nature of and and or
http://www.diveintopython.net/power_of_introspection/and_or.html