code: def test_mpi_barrier(seed, comm_nccl_opts):
      if comm_nccl_opts is None:
          pytest.skip(
              "Communicator test is disabled. You can turn it on by an option `--test-communicator`."
          )
      if len(comm_nccl_opts.devices) < 2:
          pytest.skip(
              "Communicator test is disabled. Use more than 1 gpus."
          )
  
      comm = comm_nccl_opts.comm
      device_id = int(comm_nccl_opts.device_id)
      n_devices = len(comm_nccl_opts.devices)
  
      # Just check the method can be called.
      comm.barrier()
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_mpi_barrier(seed, comm_nccl_opts) without return types