Potential confusion combining != with or

[buran]

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.

Actually the second part of your explanation (the one I have quoted) is not correct. The first part about true-testing is correct.
"y" or "n" will return "y" (i.e. first element that is considered to be True). So if you have False or None or [] or 'spam' it will return 'spam'
And 'y' and 'n' will return 'n' - i.e. the last element considered to be True

That is why answer.lower() != ("y" or "n"): is same as answer.lower() != "y":