Unpickle Custom Class 會出 error

[helioz11]

SA code 裡面有 define _Model 卻執行時後有問題，error log：

Process DAI-1:
Traceback (most recent call last):
  File "/usr/lib/python3.9/multiprocessing/process.py", line 315, in _bootstrap
    self.run()
  File "/home/kevin/my-dummydevice-venv/lib/python3.9/site-packages/iottalkpy/dai.py", line 187, in run
    self.dan.register(
  File "/home/kevin/my-dummydevice-venv/lib/python3.9/site-packages/iottalkpy/dan.py", line 461, in register
    ctx.on_register(self)
  File "/home/kevin/dummydevice/dummy-sa.py", line 109, in on_register
    model = pickle.load(f)
AttributeError: Can't get attribute '_Model' on <module 'iottalkpy.dai' from '/home/kevin/my-dummydevice-venv/lib/python3.9/site-packages/iottalkpy/dai.py'>