code: def subscribe(self, callback_url, timeout=None):
          
          url = urljoin(self._url_base, self._event_sub_url)
          headers = dict(
              HOST=urlparse(url).netloc,
              CALLBACK='<%s>' % callback_url,
              NT='upnp:event'
          )
          if timeout is not None:
              headers['TIMEOUT'] = 'Second-%s' % timeout
          resp = requests.request('SUBSCRIBE', url, headers=headers, auth=self.device.http_auth)
          resp.raise_for_status()
          return Service.validate_subscription_response(resp)
docs: Set up a subscription to the events offered by this service.