code: def export() -> None:
      node = onnx.helper.make_node(
          "ArrayFeatureExtractor",
          inputs=["x", "y"],
          outputs=["z"],
          domain="ai.onnx.ml",
      )
  
      x = np.arange(12).reshape((3, 4)).astype(np.float32)
      y = np.array([0, 1], dtype=np.int64)
      z = np.array([[0, 4, 8], [1, 5, 9]], dtype=np.float32).T
      expect(
          node,
          inputs=[x, y],
          outputs=[z],
          name="test_ai_onnx_ml_array_feature_extractor",
      )
  
imports: import numpy
  import onnx
  from onnx.backend.test.case.base import Base
  from onnx.backend.test.case.node import expect
label_desc: Use image node_id 1 for calling the ArrayFeatureExtractor obj's underlying member method code with example usage: obj.export() without return types