code: def start(self):
          
          if self._with_discovery:
              # Start the server to listen to new devices
              self.upnp.server.set_spawn(2)
              self.upnp.server.start()
          if self._with_subscribers:
              # Start the server to listen to events
              self.registry.server.set_spawn(2)
              self.registry.server.start()
docs: Start the server(s) necessary to receive information from devices.