code: def fetch_and_execute_function_to_run(self, key):
          
          (driver_id, serialized_function,
           run_on_other_drivers) = self.redis_client.hmget(
               key, ["driver_id", "function", "run_on_other_drivers"])
  
          if (utils.decode(run_on_other_drivers) == "False"
                  and self.worker.mode == ray.SCRIPT_MODE
                  and driver_id != self.worker.task_driver_id.binary()):
              return
  
          try:
              # Deserialize the function.
              function = pickle.loads(serialized_function)
              # Run the function.
              function({"worker": self.worker})
          except Exception:
              # If an exception was thrown when the function was run, we record
              # the traceback and notify the scheduler of the failure.
              traceback_str = traceback.format_exc()
              # Log the error message.
              utils.push_error_to_driver(
                  self.worker,
                  ray_constants.FUNCTION_TO_RUN_PUSH_ERROR,
                  traceback_str,
                  driver_id=ray.DriverID(driver_id))
docs: Run on arbitrary function on the worker.