The end of the other

Check out my code and tell me where's the error. Thank you.

def checkio(words_set):
if len(words_set) == 1:
    return False
for suffix in words_set:
    for word in words_set:
        if suffix != word:
            return word.endswith(suffix)

#These "asserts" using only for self-checking and not necessary for auto-testing
if __name__ == '__main__':
assert checkio({"hello", "lo", "he"}) == True, "helLO"
assert checkio({"hello", "la", "hellow", "cow"}) == False,     "hellow la cow"
    assert checkio({"walk", "duckwalk"}) == True, "duck to walk"
    assert checkio({"one"}) == False, "Only One"
    assert checkio({"helicopter", "li", "he"}) == False, "Only end"