code: async def receive_json(self, content, **kwargs):
          
          # Check the frame looks good
          if isinstance(content, dict) and "stream" in content and "payload" in content:
              # Match it to a channel
              steam_name = content["stream"]
              payload = content["payload"]
              # block upstream frames
              if steam_name not in self.applications_accepting_frames:
                  raise ValueError("Invalid multiplexed frame received (stream not mapped)")
              # send it on to the application that handles this stream
              await self.send_upstream(
                  message={
                      "type": "websocket.receive",
                      "text": await self.encode_json(payload)
                  },
                  stream_name=steam_name
              )
              return
          else:
              raise ValueError("Invalid multiplexed **frame received (no channel/payload key)")
docs: Rout the message down the correct stream.