def joinGroup(addr, interface=""):
        """
        Join a multicast group. Returns L{Deferred} of success or failure.

        If an error occurs, the returned L{Deferred} will fail with
        L{error.MulticastJoinError}.
        """

        Join a multicast group. Returns L{Deferred} of success or failure.

        If an error occurs, the returned L{Deferred} will fail with
        L{error.MulticastJoinError}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/interfaces.py