code: def test_is_triangulated(self):
      G = UndirectedGraph(
          [("A", "B"), ("A", "C"), ("B", "D"), ("C", "D")]
      )
      self.assertFalse(G.is_triangulated())
      G.add_edge("A", "D")
      self.assertTrue(G.is_triangulated())
  
imports: from pgmpy.base import UndirectedGraph
  from pgmpy.tests import help_functions
  import unittest
label_desc: Use image node_id 2 for calling the TestUndirectedGraphMethods obj's underlying member method code with example usage: obj.test_is_triangulated() without return types