string - Python: is isalnum() the same as isalpha with isdigit?

Question

Is there a way to concretely verify this? I tried to solve a coding question but it seems one of the test cases (not revealed to me) takes this as wrong. In what kinds of cases does this fail to be true?

Answer 1

There are cases when both isalpha and isdigit returns False, but isalnum returns True. So isalnum is not just a combination of the other two.

>>> 'a1'.isalpha(), 'a1'.isdigit(), 'a1'.isalnum()
(False, False, True)