装饰器计算函数耗时：

def clock(func):
    "用于计算函数耗时的装饰器"
    def funCountTime(*args, **kwargs):
        startTime = time.time()
        result = func(*args, **kwargs)
        endTime = time.time()
        timeCost = endTime - startTime
        print(f'func<{func.__name__}> timeCost: {timeCost} s')
        return result
    return funCountTime