How to organize a python project

I am new to python and trying to figure out how to do things the "right way" and encountered the following problem:

My project has a structure that looks a little this:

├─packageA │ functions.py │ __init__.py │ └─tests some_tests.py 

packageA/__init__.py is empty.

packageA/functions.py looks like this:

def some_function(x): return x*x 

And finally, tests/some_tests.py:

import packageA.functions if __name__ == '__main__': print(packageA.functions.some_function(2)) 

If I run test.py using pycharm it works fine. However, when I open up a console and start it by running python.exe ./tests/some_tests.py I get

 Traceback (most recent call last): File ".\tests\some_tests.py", line 1, in <module> import packageA.functions ModuleNotFoundError: No module named 'packageA' 

While writing this, I figured out that pycharm adds source folders to PYTHONPATH - when I turn this off I get the same error. Is the folder structure above a sensible way to structure a python project? If not, how should it be organized instead?