code: def _run_test(rank, world_size, port, expert_parallel):
      colossalai.launch(
          config=dict(),
          rank=rank,
          world_size=world_size,
          host="localhost",
          port=port,
          backend="nccl",
      )
      run_moe_init(expert_parallel)
  
file_path: ColossalAI/tests/test_moe/test_moe_group.py
imports: import pytest
  import torch.distributed
  import torch.nn
  import colossalai
  from colossalai.moe.experts import MLPExperts
  from colossalai.moe.manager import MOE_MANAGER
  from colossalai.moe.utils import sync_moe_model_param
  from colossalai.testing import assert_equal_in_group, rerun_if_address_is_in_use, spawn
  from colossalai.utils import get_current_device
label_desc: Use image node_id 2 for calling a global function with example usage: _run_test(rank, world_size, port, expert_parallel) without return types