code: def test_setdefault(self):
      BasicTestMappingProtocol.test_setdefault(self)
      d = self._empty_mapping()
      self.assertTrue(d.setdefault("key0") is None)
      d.setdefault("key0", [])
      self.assertTrue(d.setdefault("key0") is None)
      d.setdefault("key", []).append(3)
      self.assertEqual(d["key"][0], 3)
      d.setdefault("key", []).append(4)
      self.assertEqual(len(d["key"]), 2)
  
imports: import unittest
  import collections
  from test.support import Py_C_RECURSION_LIMIT
label_desc: Use image node_id 14 for calling the TestMappingProtocol obj's underlying member method code with example usage: obj.test_setdefault() without return types