code: def test_bluefog_local_size(hier_setup):
      _, true_size = mpi_env_rank_and_size()
      local_size = bf.local_size()
      assert local_size == min(2, true_size)
  
imports: import itertools
  import os
  import numpy
  import pytest
  import torch
  import networkx
  import bluefog.torch
  from common import mpi_env_rank_and_size
label_desc: Use image node_id 5 for calling a global function with example usage: test_bluefog_local_size(hier_setup) without return types