code: def test_output_gpu(self):
      model, a = self.to_gpu(self.model, self.a)
      # test outputs are overwritten
      self.expect(
          model,
          a,
          name=self.name,
          skip_opset_version=self.skip_opset_version,
          expected_num_initializers=0,
      )
  
imports: import chainer
  import chainer.functions
  from chainer import testing
  from chainer.testing import attr
  import numpy
  import pytest
  from onnx_chainer.testing import input_generator
  from onnx_chainer_tests.helper import ONNXModelTest
label_desc: Use image node_id 3 for calling the TestUnaryMathOperators obj's underlying member method code with example usage: obj.test_output_gpu() without return types