code: def testCombinationMean(self):
      g = self.g
      g.simplify(combine_edges="mean")
      self.assertTrue(g.es["weight"] == [1.5, 3, 5])
      self.assertTrue(g.es["weight2"] == [1.5, 3, 5])
  
imports: import unittest
  from igraph import Graph
label_desc: Use image node_id 5 for calling the AttributeCombinationTests obj's underlying member method code with example usage: obj.testCombinationMean() without return types