code: def after_request(self, fn):
          
          self._defer(lambda app: app.after_request(fn))
          return fn
docs: Register a function to be run after each request.
  
          Your function must take one parameter, an instance of
          :attr:`response_class` and return a new response object or the
          same (see :meth:`process_response`).
  
          As of Flask 0.7 this function might not be executed at the end of the
          request in case an unhandled exception occurred.