'Success handler.
Run by the worker if the task executes successfully.
Arguments:
retval (Any): The return value of the task.
task_id (str): Unique id of the executed task.
args (Tuple): Original arguments for the executed task.
kwargs (Dict): Original keyword arguments for the executed task.
Returns:
None: The return value of this handler is ignored.'

def on_success(self, retval, task_id, args, kwargs):

    pass
