python 判断变量是否为空(假),为空则返回默认值

In [11]: False or True
Out[11]: True

python 中的三目运算符:

In [1]: 1==1 and '123' or '456'   
Out[1]: '123'

魔幻的python语句:

In [6]: a = 1 if 1==2 else 2
In [7]: a
Out[7]: 2

In [8]: a = 1 if 1==1 else 2
In [9]: a
Out[9]: 1