It is even less tricky than you are thinking. I literally just want them to know you need to put in a `hw.py` file `print("hello world")`, and then run from the command line `python hw.py`.

The reasons for failure are myriad (I suppose you could say it is they do not understand, but I legit try, regularly spend 10-20 minutes on just this for the ones who have problems, I am not being tricky). A few are people who do not know file systems (save their `.py` file in a wrong location), a few I think just do work in environments like served jupyter notebooks so don't have any relevant software dev experience (don't know how to execute python directly or write code in a .py file), some I am pretty sure are just liars on their expertise (have a few that just leave interview when asked this question).