code: def setUp(self):
      self.demo = SEMGraph(
          ebunch=[
              ("xi1", "x1", 1.000),
              ("xi1", "x2", 2.180),
              ("xi1", "x3", 1.819),
              ("xi1", "eta1", 1.483),
              ("eta1", "y1", 1.000),
              ("eta1", "y2", 1.257),
              ("eta1", "y3", 1.058),
              ("eta1", "y4", 1.265),
              ("eta1", "eta2", 0.837),
              ("xi1", "eta2", 0.572),
              ("eta2", "y5", 1.000),
              ("eta2", "y6", 1.186),
              ("eta2", "y7", 1.280),
              ("eta2", "y8", 1.266),
          ],
          latents=["xi1", "eta1", "eta2"],
          err_corr=[
              ("y1", "y5", 0.624),
              ("y2", "y6", 2.153),
              ("y2", "y4", 1.313),
              ("y3", "y7", 0.795),
              ("y4", "y8", 0.348),
              ("y6", "y8", 1.356),
          ],
          err_var={
              "x1": 0.082,
              "x2": 0.120,
              "x3": 0.467,
              "y1": 1.891,
              "y2": 7.373,
              "y3": 5.067,
              "y4": 3.148,
              "y5": 2.351,
              "y6": 4.954,
              "y7": 3.431,
              "y8": 3.254,
              "xi1": 0.448,
              "eta1": 3.956,
              "eta2": 0.172,
          },
      )
      self.demo_lisrel = self.demo.to_lisrel()
  
      self.small_model = SEM.from_graph(
          ebunch=[("X", "Y", 0.3)],
          latents=[],
          err_var={"X": 0.1, "Y": 0.1},
      )
      self.small_model_lisrel = self.small_model.to_lisrel()
  
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 1 for calling the TestSEMAlg obj's underlying member method code with example usage: obj.setUp() without return types