code: def test_dft20_unknown_axis(self) -> None:
      self._test_model_conversion_fails(
          to_opset=19,
          model="""
              <ir_version: 9, opset_import: [ "" : 20]>
              dft_no_axis (float[N, M, 1] x, int64 dft_length, int64 axis) => (float[P, K, 2] y)
              {
                  y = DFT (x, dft_length, axis)
              }
          """,
      )
  
file_path: onnx/onnx/test/version_converter/automatic_downgrade_test.py
imports: import unittest
  import automatic_conversion_test_base
  import numpy
  import parameterized
  import onnx
  from onnx import helper
label_desc: Use image node_id 6 for calling the TestAutomaticDowngrade obj's underlying member method code with example usage: obj.test_dft20_unknown_axis() without return types