code: def test_set_state_sets_backend_state_if_it_does_not_exist(
      self,
  ) -> None:
      state, token, has_set = self._set_state(b"x")
  
      self.assertEqual(b"x", state)
      self.assertIsNotNone(token)
      self.assertTrue(has_set)
  
file_path: pytorch/test/distributed/elastic/rendezvous/rendezvous_backend_test.py
imports: from abc import ABC, abstractmethod
  from typing import Any, Callable, Optional, Tuple, cast
  from torch.distributed.elastic.rendezvous import RendezvousStateError
  from torch.distributed.elastic.rendezvous.dynamic_rendezvous import RendezvousBackend, Token
label_desc: Use image node_id 6 for calling the RendezvousBackendTestMixin obj's underlying member method code with example usage: obj.test_set_state_sets_backend_state_if_it_does_not_exist() without return types