def _setAttributes(self, reactor, done):
        """
        Set attributes on the protocol that are known only externally; this
        will be called by L{runProtocolsWithReactor} when this protocol is
        instantiated.

        @param reactor: The reactor used in this test.

        @param done: A L{Deferred} which will be fired when the connection is
           lost.
        """
        self.reactor = reactor
        self._done = done

        Set attributes on the protocol that are known only externally; this
        will be called by L{runProtocolsWithReactor} when this protocol is
        instantiated.

        @param reactor: The reactor used in this test.

        @param done: A L{Deferred} which will be fired when the connection is
           lost.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/connectionmixins.py