code: def test_output(self):
      from onnx_chainer.replace_func import as_funcnode
  
      class Model(chainer.Chain):
          def __init__(self):
              super().__init__()
  
          @as_funcnode("Shape")
          def shape(self, x):
              # ONNX Shape operator constrains to return int64 type
              return np.array(x.shape, dtype=np.int64)
  
          def forward(self, x):
              # use shape method instead of x.shape to connect graph.
              return self.shape(x)
  
      model = Model()
      x = input_generator.increasing(3, 4, 5)
  
      self.expect(model, (x,))
  
imports: import chainer
  import chainer.functions
  from chainer import testing
  import numpy
  import onnx
  import pytest
  from onnx_chainer import export
  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 TestShape obj's underlying member method code with example usage: obj.test_output() and returns: np, self