how to use?

[Jzhenli]

Hi, I have a package named demo as attached files, then compiled it to a single demo.so file,
example.zip

but when I try to use this demo.so file:

from demo.func.func_add import add
if __name__ == '__main__':
    print("3+2=", add(3,2))

it will raise error:

(.venv) pi@pi:~/so/demo33 $ python main.py
Traceback (most recent call last):
  File "/home/pi/so/demo33/main.py", line 1, in <module>
    from demo.func.func_add import add
ImportError: dynamic module does not define module export function (PyInit_demo)

would u help to check what's wrong?