code: def testCombinationFunction(self):
      g = self.g
  
      def join_dash(items):
          return "-".join(items)
  
      g.es["name"] = list("ABCDEFG")
      g.simplify(combine_edges={"weight": max, "name": join_dash})
      self.assertTrue(g.es["weight"] == [2, 3, 6])
      self.assertFalse("weight2" in g.edge_attributes())
      self.assertTrue(g.es["name"] == ["A-B", "C", "D-E-F"])
  
imports: import unittest
  from igraph import Graph
label_desc: Use image node_id 14 for calling the AttributeCombinationTests obj's underlying member method code with example usage: obj.testCombinationFunction() and returns: str