code: def do_NOTIFY(self):  # pylint: disable=invalid-name
          
          timestamp = time.time()
          headers = requests.structures.CaseInsensitiveDict(self.headers)
          seq = headers['seq']  # Event sequence number
          sid = headers['sid']  # Event Subscription Identifier
          content_length = int(headers['content-length'])
          content = self.rfile.read(content_length)
          # Find the relevant service and queue from the sid
          with _subscriptions_lock:
              subscription = _subscriptions.get(sid)
          # It might have been removed by another thread
          if subscription:
              service = subscription.service
              log.info(
                  "Event %s received for %s service on thread %s at %s", seq,
                  service.service_id, threading.current_thread(), timestamp)
              log.debug("Event content: %s", content)
              variables = parse_event_xml(content)
              # Build the Event object
              event = Event(sid, seq, service, timestamp, variables)
              # pass the event details on to the service so it can update its
              # cache.
              # pylint: disable=protected-access
              service._update_cache_on_event(event)
              # Put the event on the queue
              subscription.events.put(event)
          else:
              log.info("No service registered for %s", sid)
          self.send_response(200)
          self.end_headers()
docs: Serve a ``NOTIFY`` request.
  
          A ``NOTIFY`` request will be sent by a Sonos device when a state
          variable changes. See the `UPnP Spec §4.3 [pdf]
          <http://upnp.org/specs/arch/UPnP-arch
          -DeviceArchitecture-v1.1.pdf>`_  for details.