code: def test_get_children(self):
      self.assertListEqual(
          sorted(self.graph.get_children("diff")), ["grade"]
      )
  
imports: import unittest
  import networkx
  import numpy
  import pgmpy.tests.help_functions
  from pgmpy.base import DAG, PDAG
label_desc: Use image node_id 5 for calling the TestDAGMoralization obj's underlying member method code with example usage: obj.test_get_children() without return types