def getChallenge(peer):
        """
        Generate a challenge the client may respond to.

        @type peer: C{tuple}
        @param peer: The client's address

        @rtype: C{str}
        @return: The challenge string
        """

        Generate a challenge the client may respond to.

        @type peer: C{tuple}
        @param peer: The client's address

        @rtype: C{str}
        @return: The challenge string
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/protocols/sip.py