code: def _test_launch_worker(
      self,
      num_processes: int,
      init_pg_explicit: bool,
  ) -> None:
      lc = get_pet_launch_config(num_processes)
      pet.elastic_launch(lc, entrypoint=self._test_worker_fn)(
          init_pg_explicit
      )
  
imports: import os
  import unittest
  import numpy
  import torch
  import torch.distributed.launcher
  from torchtnt.utils.device import get_device_from_env
  from torchtnt.utils.distributed import get_process_group_backend_from_device
  from torchtnt.utils.env import init_from_env, seed
  from torchtnt.utils.test_utils import get_pet_launch_config
label_desc: Use image node_id 3 for calling the EnvTest obj's underlying member method code with example usage: obj._test_launch_worker(num_processes, init_pg_explicit) without return types