docstr: Test difference_in_hierarchy returns expected value for two nodes, and for identical nodes.
code: def test_difference_in_hierarchy(self):
      """Test difference_in_hierarchy returns expected value for two nodes, and for identical nodes."""
      self.assertTrue(
          np.allclose(
              self.vectors.difference_in_hierarchy(
                  "dog.n.01", "dog.n.01"
              ),
              0,
          )
      )
      self.assertTrue(
          np.allclose(
              self.vectors.difference_in_hierarchy(
                  "mammal.n.01", "dog.n.01"
              ),
              0.9384287,
          )
      )
      self.assertTrue(
          np.allclose(
              self.vectors.difference_in_hierarchy(
                  "dog.n.01", "mammal.n.01"
              ),
              -0.9384287,
          )
      )
  
imports: import logging
  import os
  import tempfile
  import unittest
  import numpy
  from gensim.models.poincare import PoincareRelations, PoincareModel, PoincareKeyedVectors
  from gensim.test.utils import datapath
label_desc: Use image node_id 19 for calling the TestPoincareKeyedVectors obj's underlying member method code with example usage: obj.test_difference_in_hierarchy() without return types