code: def test_minimal_dseparator(self):
      # Without latent variables
  
      dag1 = DAG([("A", "B"), ("B", "C")])
      self.assertEqual(
          dag1.minimal_dseparator(start="A", end="C"), {"B"}
      )
  
      dag2 = DAG(
          [("A", "B"), ("B", "C"), ("C", "D"), ("A", "E"), ("E", "D")]
      )
      self.assertEqual(
          dag2.minimal_dseparator(start="A", end="D"), {"C", "E"}
      )
  
      dag3 = DAG(
          [
              ("B", "A"),
              ("B", "C"),
              ("A", "D"),
              ("D", "C"),
              ("A", "E"),
              ("C", "E"),
          ]
      )
      self.assertEqual(
          dag3.minimal_dseparator(start="A", end="C"), {"B", "D"}
      )
  
      # With latent variables
  
      dag_lat1 = DAG([("A", "B"), ("B", "C")], latents={"B"})
      self.assertIsNone(dag_lat1.minimal_dseparator(start="A", end="C"))
  
      dag_lat2 = DAG(
          [("A", "D"), ("D", "B"), ("B", "C")], latents={"B"}
      )
      self.assertEqual(
          dag_lat2.minimal_dseparator(start="A", end="C"), {"D"}
      )
  
      dag_lat3 = DAG(
          [("A", "B"), ("B", "D"), ("D", "C")], latents={"B"}
      )
      self.assertEqual(
          dag_lat3.minimal_dseparator(start="A", end="C"), {"D"}
      )
  
      dag_lat4 = DAG(
          [("A", "B"), ("B", "C"), ("A", "D"), ("D", "C")],
          latents={"D"},
      )
      self.assertIsNone(dag_lat4.minimal_dseparator(start="A", end="C"))
  
      dag_lat5 = DAG(
          [("A", "B"), ("B", "C"), ("A", "D"), ("D", "E"), ("E", "C")],
          latents={"E"},
      )
      self.assertEqual(
          dag_lat5.minimal_dseparator(start="A", end="C"), {"B", "D"}
      )
  
imports: import unittest
  import networkx
  import numpy
  import pgmpy.tests.help_functions
  from pgmpy.base import DAG, PDAG
label_desc: Use image node_id 22 for calling the TestDAGCreation obj's underlying member method code with example usage: obj.test_minimal_dseparator() without return types