code: def test_active_trail_nodes_args(self):
      self.assertListEqual(
          sorted(self.G2.active_trail_nodes("d", observed="g")),
          ["d", "l", "s"],
      )
      self.assertListEqual(
          sorted(self.G2.active_trail_nodes("l", observed="g")),
          ["d", "l", "s"],
      )
      self.assertListEqual(
          sorted(self.G2.active_trail_nodes("s", observed=["g", "l"])),
          ["d", "s"],
      )
      self.assertListEqual(
          sorted(self.G2.active_trail_nodes("s", observed=["d", "l"])),
          ["s"],
      )
  
imports: import unittest
  import networkx
  import pandas
  import numpy
  from pgmpy.models import NaiveBayes
  from pgmpy.independencies import Independencies
label_desc: Use image node_id 4 for calling the TestNaiveBayesMethods obj's underlying member method code with example usage: obj.test_active_trail_nodes_args() without return types