code: def test_new_attributes_cannot_be_set_on_child_of_seal(self):
      m = mock.Mock()
      m.test.test2 = 1
  
      mock.seal(m)
      with self.assertRaises(AttributeError):
          m.test.test3 = 1
  
imports: import unittest
  from unittest import mock
label_desc: Use image node_id 5 for calling the TestSealable obj's underlying member method code with example usage: obj.test_new_attributes_cannot_be_set_on_child_of_seal() without return types