code: def test_cost(self):
      costs = {"diff": 4, "sat": 0, "reco": 0, "grade": 12, "intel": 12}
      for var, expected_cost in costs.items():
          self.assertEqual(
              self.elimination_order.cost(var), expected_cost
          )
  
imports: from unittest import TestCase
  import numpy
  import pandas
  from pgmpy.inference.EliminationOrder import BaseEliminationOrder, MinFill, MinNeighbors, MinWeight, WeightedMinFill
  from pgmpy.models import BayesianNetwork
label_desc: Use image node_id 2 for calling the TestWeightedMinFill obj's underlying member method code with example usage: obj.test_cost() without return types