code: def test_output(self):
      model = self.get_model()
      x = np.zeros((10, 4, 256, 256), dtype=np.float32)
  
      self.expect(model, x, train=True)
  
imports: import chainer
  import chainer.functions
  import chainer.links
  from chainer import testing
  import numpy
  from onnx_chainer.testing import input_generator
  from onnx_chainer_tests.helper import get_initializer_names
  from onnx_chainer_tests.helper import ONNXModelTest
label_desc: Use image node_id 2 for calling the TestGroupNormalization obj's underlying member method code with example usage: obj.test_output() without return types