Всем привет пробую примеры из доки multiprocessing https://docs.python.org/3/library/multiprocessing.html#synchronization-between-processes почему то этот пример

Question

Всем привет пробую примеры из доки multiprocessing https://docs.python.org/3/library/multiprocessing.html#synchronization-between-processes почему то этот пример

выдает ошибку:
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/spawn.py", line 116, in spawn_main
exitcode = _main(fd, parent_sentinel)
File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/spawn.py", line 126, in _main
self = reduction.pickle.load(from_parent)
File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/synchronize.py", line 110, in setstate
self._semlock = _multiprocessing.SemLock._rebuild(*state)
FileNotFoundError: [Errno 2] No such file or directory

MacOS, Python 3.8.1

в чем проблема?