Importing module from "outer" directory [Python]

Question

I have seen a lot of answers over this simple problem but I can't find a good solution for such, even a workable solution; the problem is, I have this proyect structure

parent_folder
   |
   |__folder1
   |    |_____ __init__.py
   |    |_____ file1.py 
   |
   |__folder2
        |_____ __init__.py  
        |_____file2.py  

I want to call a function (lets name it function2) from file2.py inside file1.py, but when doing an import like this:

# inside file1.py

from folder2.file import function2

I get the following error:

ModuleNotFoundError: No module named 'folder2'

Then I tried using absolute import, so the code looked like:

# inside file1.py

from ..folder2.file2 import function2

And I get the following error:

ImportError: attempted relative import with no known parent package

And finally I tried adding such directory to my path using the following code:

#inside file1.py

import sys
sys.path.append("..")

from ..folder2.file2 import function2

And still, get the same error:

ImportError: attempted relative import with no known parent package

What is the definitive CLEAN solution for such problem?,I would appreciate an answer, thanks

NOTE: My current Python version is 3.8 and the code is running under Windows 10

Answer 1

file1.py

import os
import sys
sys.path.append(os.path.dirname(os.getcwd()))
from folder2.file2 import function2