import time

def performance(f):

    def fn(*args,**kw):

        t1 = time.time()

        r = f(*args,**kw)

        t2 = time.time()

        print 'call %s() in %fm' %(f.__name__,(t2-t1))

        #return f(*args,**kw)

       # return r（返回r和返回上面一行代码有上面区别吗 为上面要把 f(*args,**kw)赋值给r再返回r）？？？？？？？？？？？？？？？？

    return fn

@performance

def factorial(n):

    return reduce(lambda x,y: x*y, range(1, n+1))

print factorial(10)