a task that always places a fresh order when called is not idempotent, but a task that cancels an existing order is idempotent. Operations that only read the state of the world and do not have any side effects are nullipotent. As Celery architecture relies on tasks being idempotent, it is important to try to study all the side effects of a non-idempotent task and convert it into an idempotent task. You can do this by either checking whether the tasks have been executed previously (if it was, then abort)
