code: def setUp(self):
      # Model example taken from Constructing Separators and Adjustment Sets
      # in Ancestral Graphs UAI 2014.
      self.model = BayesianNetwork(
          [
              ("x1", "y1"),
              ("x1", "z1"),
              ("z1", "z2"),
              ("z2", "x2"),
              ("y2", "z2"),
          ]
      )
      self.infer = CausalInference(self.model)
  
imports: import unittest
  import numpy
  import numpy.testing
  import pandas
  from pgmpy.factors.discrete import TabularCPD
  from pgmpy.inference.CausalInference import CausalInference
  from pgmpy.models import BayesianNetwork
label_desc: Use image node_id 1 for calling the TestAdjustmentSet obj's underlying member method code with example usage: obj.setUp() without return types