code: def testCombinationNone(self):
      g = self.g
      g.simplify()
      self.assertTrue(sorted(g.edge_attributes()) == [])
  
imports: import unittest
  from igraph import Graph
label_desc: Use image node_id 19 for calling the AttributeCombinationTests obj's underlying member method code with example usage: obj.testCombinationNone() without return types