docstr: Test descendants returns expected list and returns empty list for lowest node in hierarchy.
code: def test_descendants(self):
      """Test descendants returns expected list and returns empty list for lowest node in hierarchy."""
      expected = [
          "terrier.n.01",
          "sporting_dog.n.01",
          "spaniel.n.01",
          "water_spaniel.n.01",
          "irish_water_spaniel.n.01",
      ]
      self.assertEqual(self.vectors.descendants("dog.n.01"), expected)
      self.assertEqual(
          self.vectors.descendants("dog.n.01", max_depth=3),
          expected[:3],
      )
  
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 16 for calling the TestPoincareKeyedVectors obj's underlying member method code with example usage: obj.test_descendants() without return types