>>> def myfunction(a,b):
...     return a*b
...
>>> mylist = [1,2,3,4,5]
>>> print reduce(myfunction, mylist)
120
 
#上面的代码相当于：
>>>print ((((1*2)*3)*4)*5)
120
 
#也可以直接使用操作符模块来替代函数
>>> import operator
>>> mylist = [1,2,3,4,5]
>>> print reduce(operator.mul, mylist)
120
>>> print reduce(operator.add, mylist)
15