class Napis:
    def __init__(self, s):
        self._s = s
    def __lt__(self, o):
        return len(self._s) < len(o._s)
    def __repr__(self):
        return str(self._s)
napisy = (Napis("aaaaaaaa"), Napis("a"), Napis("aaa"), Napis("bb"))
print sorted(napisy)