code: def _test_replace_func(self, fn, xs, set_grad=False):
      def make_list(v):
          if isinstance(v, (list, tuple)):
              return list(v)
          else:
              return [v]
  
      xvs = [x for x in xs if isinstance(x, chainer.Variable)]
      rfn = as_funcnode("fn")(fn)
      eys = make_list(fn(*xs))
      egxs = chainer.grad(eys, xvs, set_grad=set_grad)
      ays = make_list(rfn(*xs))
      agxs = chainer.grad(ays, xvs, set_grad=set_grad)
      assert len(eys) == len(ays)
      for ay, ey in zip(ays, eys):
          np.testing.assert_allclose(ay.array, ey.array)
      assert len(egxs) == len(agxs)
      for agx, egx in zip(agxs, egxs):
          if egx is None:
              assert egx is None
          else:
              np.testing.assert_allclose(agx.array, egx.array)
  
imports: import os
  import warnings
  import chainer
  import chainer.functions
  import chainer.links
  from chainer import testing
  import numpy
  import onnx
  import pytest
  from onnx_chainer import export
  from onnx_chainer import export_testcase
  from onnx_chainer import onnx_helper
  from onnx_chainer.replace_func import as_funcnode
  from onnx_chainer.replace_func import fake_as_funcnode
  from onnx_chainer.testing import input_generator
  from onnx_chainer_tests.helper import ONNXModelChecker
  from onnx_chainer_tests.helper import ONNXModelTest
label_desc: Use image node_id 1 for calling the TestReplaceFuncBackward obj's underlying member method code with example usage: obj._test_replace_func(fn, xs, set_grad) and returns: list, list