code: def startAlertListener(self, callback=None):
          
          notifier = AlertListener(self, callback)
          notifier.start()
          return notifier
docs: Creates a websocket connection to the Plex Server to optionally recieve
              notifications. These often include messages from Plex about media scans
              as well as updates to currently running Transcode Sessions.
  
              NOTE: You need websocket-client installed in order to use this feature.
              >> pip install websocket-client
  
              Parameters:
                  callback (func): Callback function to call on recieved messages.
  
              raises:
                  :class:`plexapi.exception.Unsupported`: Websocket-client not installed.