import time

def time_cost(tag=None):
    """
    装饰器,自定义函数耗时打印信息
    :param tag: 可选,自定义标志(说明当前执行的函数)
    """
    def decorator(func):
        def wrapper(*args, **kwargs):
            start_time = time.time()
            result = func(*args, **kwargs)
            end_time = time.time()
            label = tag if tag is not None else func.__name__
            print(f"耗时统计[{label}]: {(end_time - start_time)*1000:.2f} 毫秒")
            return result
        return wrapper
    return decorator