code: def test_get_ivs_union(self):
      scale = {}
      self.assertSetEqual(
          self.union.get_ivs(
              "yrsmill", "unionsen", scaling_indicators=scale
          ),
          set(),
      )
      self.assertSetEqual(
          self.union.get_ivs(
              "deferenc", "unionsen", scaling_indicators=scale
          ),
          set(),
      )
      self.assertSetEqual(
          self.union.get_ivs(
              "laboract", "unionsen", scaling_indicators=scale
          ),
          set(),
      )
      self.assertSetEqual(
          self.union.get_ivs(
              "deferenc", "laboract", scaling_indicators=scale
          ),
          set(),
      )
      self.assertSetEqual(
          self.union.get_ivs(
              "age", "laboract", scaling_indicators=scale
          ),
          {"yrsmill"},
      )
      self.assertSetEqual(
          self.union.get_ivs(
              "age", "deferenc", scaling_indicators=scale
          ),
          {"yrsmill"},
      )
  
imports: import os
  import unittest
  import networkx
  import numpy
  import numpy.testing
  from pgmpy.models import SEM, SEMAlg, SEMGraph
label_desc: Use image node_id 14 for calling the TestSEMGraph obj's underlying member method code with example usage: obj.test_get_ivs_union() without return types