Mistake: > ...the statement even though logical, is not technically right because if we start from the left cell[0][0] == cell[1][1] would evaluate to True and

Mistake: > ...the statement even though logical, is not technically right because if we start from the left cell[0][0] == cell[1][1] would evaluate to True and then True == cell[2][2] would evaluate to False given that the cell contains a char. Interviewer seemed confident ("is not technically right") which confused the candidate: > I told the candidate about the same and he agreed but he was confused at the same time Candidates are already in a high stress situation, you don't want to add to it unless you really know what you are doing (i.e. you are specifically looking for deep language mastery). Interviewer has correctly realized they've done this and learned from it: kudos to them even if too late for this candidate :)