code: def test_nominal(self):
      p = pd.Series([0, 0, 1, 1])
      q = pd.DataFrame([[0.5, 0.5], [0.5, 0.5], [0.5, 0.5], [0.5, 0.5]])
      expected = {cl: _evaluate(p, q[cl]) for cl in [0, 1]}
      actual = ot_distance(p, q, mode="nominal")
      assert expected == actual
  
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 10 for calling the TestOtBiasScan obj's underlying member method code with example usage: obj.test_nominal() without return types