code: def test_retain_cpu(param):
      check_retain(False, param)
  
imports: import functools
  import chainer
  import copy
  from chainer.backends.cuda import cupy
  import chainer.testing
  import chainer.testing.attr
  import numpy
  import pytest
  import chainermn
  from chainer.functions import sigmoid
  from chainer.functions import mean_squared_error
label_desc: Use image node_id 9 for calling a global function with example usage: test_retain_cpu(param) without return types