import queue

 import contextlib

 import time

 @contextlib.contextmanager

 def worker_state(xxx,val):

     xxx.append(val)

     print("before",xxx)

     try:

         time.sleep(1)

         yield

     finally:

         xxx.remove(val)

         print("after",xxx)

 if __name__ == '__main__':

     q = queue.Queue()

     q.put("")

     li = []

     with worker_state(li,1):

         q.get()