agree to disagree. As I see your point of view valid I also think of it like this: Ok, I know how to permuate a list with itertools, but it's crucial for me to know what exaclty permutation is and how the alghoritm look like

Please read the issue posted above. Understanding the flaw, you can re-write and re-submit your code.

Best of luck!

As far as I can tell, this doesn't hurt performance. You'd still have to do a full pass regardless; thus, you can't stop.