def _deliverBody_CONNECTED(self, protocol):
        """
        It is invalid to attempt to deliver data to a protocol when it is
        already being delivered to another protocol.
        """
        raise RuntimeError(
            u"Response already has protocol %r, cannot deliverBody "
            u"again" % (self._bodyProtocol,))

        It is invalid to attempt to deliver data to a protocol when it is
        already being delivered to another protocol.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/_newclient.py