1 import queue
 2 import contextlib
 3 import time
 4 @contextlib.contextmanager
 5 def worker_state(xxx,val):
 6     xxx.append(val)
 7     print("before",xxx)
 8     try:
 9         time.sleep(1)
10         yield
11     finally:
12         xxx.remove(val)
13         print("after",xxx)
14 
15 if __name__ == ‘__main__‘:
16     q = queue.Queue()
17     q.put("123")
18     li = []
19     with worker_state(li,1):
20         q.get()

1 C:\Python35\python3.exe F:/Python/taochen/day22/a15.py
2 before [1]
3 after []
4 
5 Process finished with exit code 0