Python比较评估

Question

根据python文档,x<y<z比较被转换为x<y and y<z,表达式y最多只评估一次.
现在我的问题是,表达式y(看下面的代码)在这里只评估一次吗？

if(x<y and y<z):

Answer 1

两次:

>>> def f():
...   print "F called"
...   return 1
...
>>> 0 < f() < 100
F called
True
>>> 0 < f() and f() < 100
F called
F called
True
>>> if (0 < f() and f() < 100):
...   print True
...
F called
F called
True
>>>