def dataReceived(self, data):
        """
        Data was received from the network.  Process it.
        """
        # If we're currently handling a request, buffer this data.
        if self._handlingRequest:
            self._dataBuffer.append(data)
            if (
                    (sum(map(len, self._dataBuffer)) >
                     self._optimisticEagerReadSize)
                    and not self._waitingForTransport
            ):
                # If we received more data than a small limit while processing
                # the head-of-line request, apply TCP backpressure to our peer
                # to get them to stop sending more request data until we're
                # ready.  See docstring for _optimisticEagerReadSize above.
                self._networkProducer.pauseProducing()
            return
        return basic.LineReceiver.dataReceived(self, data)

        Data was received from the network.  Process it.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/http.py