open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi all,
I'm very new to Telemac. I installed version v8p2r0, with python 3. I'm now trying to run some example cases, say "m2wave". It seems it correctly runs, but when I try to run the validation script vnv_m2wave.py, the following error comes out:

Traceback (most recent call last):
File "C:\Users\simon\Desktop\m2wave\vnv_m2wave.py", line 5, in <module>
from vvytel.vnv_study import AbstractVnvStudy
ImportError: No module named vvytel.vnv_study

I suppose it has something to do with PYTHONPATH, but if I set the following:
set HOMETEL=C:\opentelemac-mascaret\v8p2r0
set PYTHONPATH=%HOMETEL%\scripts\python3

I get a new error:
Traceback (most recent call last):
File "C:\Users\simon\Desktop\m2wave\vnv_m2wave.py", line 5, in <module>
from vvytel.vnv_study import AbstractVnvStudy
File "C:\opentelemac-mascaret\v8p2r0\scripts\python3\vvytel\vnv_study.py", line 6, in <module>
from abc import ABC, abstractmethod
ImportError: cannot import name ABC


Any suggestion would be really appreciated,
Thanks

Simon