def setResponse(response):
        """
        Extract a username and possibly a password from a response and
        assign them to C{username} and C{password} instance variables.

        @param response: A decoded response.
        @type response: L{bytes}

        @see: L{credentials.IUsernamePassword} or
            L{credentials.IUsernameHashedPassword}
        """

        Extract a username and possibly a password from a response and
        assign them to C{username} and C{password} instance variables.

        @param response: A decoded response.
        @type response: L{bytes}

        @see: L{credentials.IUsernamePassword} or
            L{credentials.IUsernameHashedPassword}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/interfaces.py