code: def test_check_closed(self):
      f = dumbdbm.open(_fname, "c")
      f.close()
  
      for meth in (
          partial(operator.delitem, f),
          partial(operator.setitem, f, "b"),
          partial(operator.getitem, f),
          partial(operator.contains, f),
      ):
          with self.assertRaises(dumbdbm.error) as cm:
              meth("test")
          self.assertEqual(
              str(cm.exception), "DBM object has already been closed"
          )
  
      for meth in (
          operator.methodcaller("keys"),
          operator.methodcaller("iterkeys"),
          operator.methodcaller("items"),
          len,
      ):
          with self.assertRaises(dumbdbm.error) as cm:
              meth(f)
          self.assertEqual(
              str(cm.exception), "DBM object has already been closed"
          )
  
imports: import contextlib
  import io
  import operator
  import os
  import stat
  import unittest
  import dbm.dumb
  from test import support
  from test.support import os_helper
  from functools import partial
label_desc: Use image node_id 17 for calling the DumbDBMTestCase obj's underlying member method code with example usage: obj.test_check_closed() without return types