Dear Friends,
It seems that I manage to find a problem with Python ... version 3.6.3
Attached is a PY file designed to solve a puzzle: see function makeGame1

To find a solution run: doFind() 
>>> doFind()

----> counter: 11735841 rec depth: 2367
86792-719
72581-938
916-398--
--9378-97
3985-4859
27-2879--
--819-698
937-69782
812-78561
----> counter: 29203691
>>> 

It takes a few seconds to come up with a solution (deep recursive exhaustive search)
if you switch between lines 109 <==> 110 then it restart Python !?!?!?!?! (see below)

>>> doFind()

=============================== RESTART: Shell ===============================
>>> 

Dr. Shimon Cohen 
shamon51@gmail.com