code: def test_not_hashable_nodes(self):
      ts = graphlib.TopologicalSorter()
      self.assertRaises(TypeError, ts.add, dict(), 1)
      self.assertRaises(TypeError, ts.add, 1, dict())
      self.assertRaises(TypeError, ts.add, dict(), dict())
  
imports: import graphlib
  import os
  import unittest
  from test.support.script_helper import assert_python_ok
label_desc: Use image node_id 15 for calling the TestTopologicalSort obj's underlying member method code with example usage: obj.test_not_hashable_nodes() without return types