code: def test_mnist(use_chx):
      check_mnist(False, use_chx)
  
imports: import os
  import pytest
  import sys
  import tempfile
  import warnings
  import chainer
  import chainer.functions
  import chainer.links
  import chainer.testing
  from chainer import training
  from chainer.training import extensions
  import chainermn
  from chainermn.testing import get_device
  from chainermn.extensions.checkpoint import create_multi_node_checkpointer
label_desc: Use image node_id 2 for calling a global function with example usage: test_mnist(use_chx) without return types