code: def ray_start_distributed_multigpu_2_nodes_4_gpus():
      # The cluster has a setup of 2 nodes, each node with 2
      # GPUs. Each actor will be allocated 2 GPUs.
      ray.init("auto")
      yield
      clean_up()
      ray.shutdown()
  
file_path: ray/python/ray/util/collective/tests/conftest.py
imports: import logging
  import pytest
  import ray
  from ray.util.collective.collective_group.nccl_collective_group import _get_comm_key_from_devices, _get_comm_key_send_recv
  from ray.util.collective.const import get_store_name
label_desc: Use image node_id 4 for calling a global function with example usage: ray_start_distributed_multigpu_2_nodes_4_gpus() without return types