import time

def performance(f):

    def fn(*args,**kw):

        t_start = time.time()

        rnt = f(args,kw)

        t_end = time.time()

        print 'call %s() in %fs.' % (f.__name__,t_end-t_start)

        return rnt

    return fn

@performance

def factorial(n):

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

print factorial(10)