code: def test_evaluate_symmetry(self):
      a = _evaluate(sd1, sd2, num_iters=1000)
      b = _evaluate(sd2, sd1, num_iters=1000)
      assert (
          abs(a - b) < 1e-8
      ), f"EMD must be symmetric, got {a} and {b}"
  
imports: import numpy
  import pandas
  from aif360.metrics.ot_metric import _normalize, _transform, _evaluate
  from aif360.sklearn.metrics import ot_distance
  from ot import emd2
  import unittest
  from unittest import TestCase
label_desc: Use image node_id 4 for calling the TestEvaluate obj's underlying member method code with example usage: obj.test_evaluate_symmetry() without return types