python 报错原因及解决方法

错误1
错误代码

import time
def timer(func):
    def deco():
        start_time=time.time()
        func()
        stop_time=time.time()
        print("运行方法耗时%s"%(stop_time-start_time))
    return deco    #此行没有缩进导致错误
@timer
def test1():
    time.sleep(2)
    print("in the test1")
test1()

输出：

Traceback (most recent call last):
  File "D:/workspace/Pycharm/study/day4/装饰器+高阶函数.py", line 18, in <module>
    test1()
TypeError: 'NoneType' object is not callable

错误原因：
return 没有缩进