Potential confusion combining != with or

[ndc85430]

answer.lower() != ("y" or "n"):

No-one has explained why this is wrong. In Python (and other languages too, actually), all values can be tested for being True or False (see the docs). Non-empty strings are treated as True, so the expression "y" or "n" evaluates to True. You then compare the return value of answer.lower() with True and the expression answer.lower() != True will always evaluate to True because answer.lower() returns a string and values of different types (string and bool here) will never be equal.