code: def variant_turnaround(self, reference, expected_result=None):
      if expected_result is None:
          expected_result = reference
      from ..extensions import _demo_identity
  
      self.identical(expected_result, _demo_identity(reference))
  
file_path: turicreate/src/python/turicreate/test/test_extensions.py
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  import unittest
  from ..data_structures.sarray import SArray
  from ..data_structures.sframe import SFrame
  import sys
  import random
  from .._cython.cy_variant import _debug_is_flexible_type_encoded
  import pytest
label_desc: Use image node_id 2 for calling the VariantCheckTest obj's underlying member method code with example usage: obj.variant_turnaround(reference, expected_result) without return types