code: def test_implicit_param(self):
      class Model(chainer.Chain):
          def __init__(self):
              super(Model, self).__init__()
              self.frac = chainer.Parameter(
                  np.array(2, dtype=np.float32)
              )
  
          def forward(self, x):
              return x / self.frac
  
      x = chainer.Variable(np.array(1, dtype=np.float32))
      self.expect(Model(), x, name="implicit_param")
  
imports: import unittest
  import chainer
  import chainer.functions
  import chainer.links
  from chainer import testing
  import numpy
  import pytest
  from onnx_chainer import export
  from onnx_chainer.export import RetainInputHook
  from onnx_chainer.testing import input_generator
  from onnx_chainer_tests.helper import ONNXModelTest
label_desc: Use image node_id 1 for calling the TestImplicitInput obj's underlying member method code with example usage: obj.test_implicit_param() and returns: unknown