pathlib error - pathlib not being found even when it is installed

[mooseman]

Hi re0ah -
This looks like a really promising project - I'm keen to help where I can with testing (as I'm not great with assembly coding :) ) .
Oh, and a huge thanks for releasing it as "public domain" - I'm a real "PD weenie" and LOVE supporting PD projects!

I found this error when trying to build the code -

andy@obsidian:/nameless-OS16$ sudo make run
rm -rf source/.bin
rm -rf source/bootload/.bin
rm -rf programs/*.bin
rm -rf images
make[1]: Entering directory '/home/andy/nameless-OS16/source/bootload'
nasm -f bin bootload.asm -o bootload.bin
make[1]: Leaving directory '/home/andy/nameless-OS16/source/bootload'
make[1]: Entering directory '/home/andy/nameless-OS16/source'
nasm -f bin kernel.asm -o kernel.bin
python pre_replace.py
Traceback (most recent call last):
File "pre_replace.py", line 3, in
from pathlib import Path
ImportError: No module named pathlib
make[1]: *** [Makefile:5: all] Error 1
make[1]: Leaving directory '/home/andy/nameless-OS16/source'
make: *** [Makefile:12: os16.flp] Error 2
andy@obsidian:/nameless-OS16$

( BTW, I'm on Linux Mint 20.1 - I installed python-pathlib2 (version 2.3.5-1ubuntu1).
I got the error as shown above so I installed pathlib. I got the error again - weird!
So - hoping you can help here as I'm very keen to get the OS working - I'll test it in VirtualBox.
Many thanks - bye for now -
Andy (mooseman)