一个测量python 函数运行时间的 decorator

#coding=utf-8
import timeit,math
class TimeMeth(object):
def __init__(self, orig_func):
self.f = orig_func

def __call__(self, *args, **kwargs):
start = timeit.default_timer()
r = self.f(*args, **kwargs)
end = timeit.default_timer()
print "The running time for %s:%2f"%(self.f.__name__, end-start)
return r

@TimeMeth
def f(n):
r = 0
for i in range(1, n):
t = math.factorial(i)
r = r + t

return r

if __name__ == '__main__':
f(5000)

请指教