code: def export() -> None:
      node = onnx.helper.make_node("Sign", ["x"], ["y"], name="test")
  
      x = np.array([-1.0, 4.5, -4.5, 3.1, 0.0, 2.4, -5.5]).astype(
          np.float32
      )
      y = np.array([-1.0, 1.0, -1.0, 1.0, 0.0, 1.0, -1.0]).astype(
          np.float32
      )
  
      graph = onnx.helper.make_graph(
          nodes=[node],
          name="SingleSign",
          inputs=[
              onnx.helper.make_tensor_value_info(
                  "x", onnx.TensorProto.FLOAT, [7]
              )
          ],
          outputs=[
              onnx.helper.make_tensor_value_info(
                  "y", onnx.TensorProto.FLOAT, [7]
              )
          ],
      )
      model = onnx.helper.make_model_gen_version(
          graph,
          producer_name="backend-test",
          opset_imports=[onnx.helper.make_opsetid("", 9)],
      )
      expect(model, inputs=[x], outputs=[y], name="test_sign_model")
  
imports: import numpy
  import onnx
  from onnx.backend.test.case.base import Base
  from onnx.backend.test.case.model import expect
label_desc: Use image node_id 1 for calling the SingleSign obj's underlying member method code with example usage: obj.export() without return types