code: def test_result_reduce_ddp():
      spawn_launch(result_reduce_ddp_fn, [torch.device("cpu")] * 2)
  
file_path: pytorch-lightning/tests/tests_pytorch/core/test_results.py
imports: from functools import partial
  import torch
  import torch.distributed
  from lightning.fabric.plugins.environments import LightningEnvironment
  from lightning.pytorch.accelerators import CPUAccelerator, CUDAAccelerator, MPSAccelerator
  from lightning.pytorch.strategies import DDPStrategy
  from lightning.pytorch.strategies.launchers import _MultiProcessingLauncher
  from lightning.pytorch.trainer.connectors.logger_connector.result import _Sync
  from tests_pytorch.helpers.runif import RunIf
  from tests_pytorch.models.test_tpu import wrap_launch_function
label_desc: Use image node_id 3 for calling a global function with example usage: test_result_reduce_ddp() without return types