code: def test_update_node_parents_bm_constructor(self):
      self.graph = DAG([("a", "b"), ("b", "c")])
      self.assertListEqual(list(self.graph.predecessors("a")), [])
      self.assertListEqual(list(self.graph.predecessors("b")), ["a"])
      self.assertListEqual(list(self.graph.predecessors("c")), ["b"])
  
imports: import unittest
  import networkx
  import numpy
  import pgmpy.tests.help_functions
  from pgmpy.base import DAG, PDAG
label_desc: Use image node_id 16 for calling the TestDAGCreation obj's underlying member method code with example usage: obj.test_update_node_parents_bm_constructor() without return types