code: def test_class_init(self):
      phi1 = DiscreteFactor(["x1", "x2", "x3"], [2, 3, 2], range(12))
      phi2 = DiscreteFactor(["x3", "x4", "x1"], [2, 2, 2], range(8))
      factor_set1 = FactorSet(phi1, phi2)
      self.assertEqual({phi1, phi2}, factor_set1.get_factors())
  
file_path: pgmpy/pgmpy/tests/test_factors/test_FactorSet.py
imports: import unittest
  from pgmpy.factors import FactorSet
  from pgmpy.factors.discrete import DiscreteFactor
label_desc: Use image node_id 2 for calling the TestFactorSet obj's underlying member method code with example usage: obj.test_class_init() without return types