code: def testCombinationDefault(self):
      g = self.g
      g.simplify(combine_edges={None: "max"})
      self.assertTrue(g.es["weight"] == [2, 3, 6])
      self.assertTrue(g.es["weight2"] == [2, 3, 6])
  
imports: import unittest
  from igraph import Graph
label_desc: Use image node_id 15 for calling the AttributeCombinationTests obj's underlying member method code with example usage: obj.testCombinationDefault() without return types