@api_endpoint
    def unsub(self, id_):
        self.do_unsub(id_, False)
L{isIPAddress} should return C{False} for the empty string.
dataset/ETHPy150Open django-ddp/django-ddp/dddp/api.py/DDP.unsub--crossover with--dataset/ETHPy150Open kuri65536/python-for-android/python-modules/twisted/twisted/test/test_abstract.py/AddressTests.test_emptyString