code: def update_custom_params(api_key, api_secret, video_key, params):
      
      formatted_params = {'custom.{}'.format(k): v for k,v in params.items()}
  
      # Setup API client
      jwplatform_client = jwplatform.Client(api_key, api_secret)
      logging.info("Updating Video")
      try:
          response = jwplatform_client.videos.update(
              video_key=video_key,
              **formatted_params)
      except jwplatform.errors.JWPlatformError as e:
          logging.error("Encountered an error updating the video\n{}".format(e))
          sys.exit(e.message)
      logging.info(response)
docs: Function which allows you to update a video's custom params. Custom params are indicated by key-values of
      "custom.<key>" = "<value>" so they must be provided as a dictionary and passed to the platform API call.
  
      :param api_key: <string> JWPlatform api-key
      :param api_secret: <string> JWPlatform shared-secret
      :param video_key: <string> Video's object ID. Can be found within JWPlayer Dashboard.
      :param params: Custom params in the format of a dictionary, e.g.
  
          >>> params = {'year': '2017', 'category': 'comedy'}
          >>> update_custom_params('XXXXXXXX', 'XXXXXXXXXXXXXXXXX', 'dfT6JSb2', params)
  
      :return: None