def test_unique(self):
        """
        All of the response code globals (for example C{RESTART_MARKER_REPLY} or
        C{USR_NAME_OK_NEED_PASS}) have unique values and are present in the
        C{RESPONSE} dictionary.
        """
        allValues = set(ftp.RESPONSE)
        seenValues = set()

        for key, value in vars(ftp).items():
            if isinstance(value, str) and key.isupper():
                self.assertIn(
                    value, allValues,
                    "Code %r with value %r missing from RESPONSE dict" % (
                        key, value))
                self.assertNotIn(
                    value, seenValues,
                    "Duplicate code %r with value %r" % (key, value))
                seenValues.add(value)

        All of the response code globals (for example C{RESTART_MARKER_REPLY} or
        C{USR_NAME_OK_NEED_PASS}) have unique values and are present in the
        C{RESPONSE} dictionary.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ftp.py