def test_PASSBeforeUSER(self):
        """
        Issuing PASS before USER should give an error.
        """
        return self.assertCommandFailed(
            'PASS foo',
            ["503 Incorrect sequence of commands: "
             "USER required before PASS"])

        Issuing PASS before USER should give an error.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ftp.py