code: def keys_helper(self, f):
      keys = sorted(f.keys())
      dkeys = sorted(self._dict.keys())
      self.assertEqual(keys, dkeys)
      return keys
  
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 14 for calling the DumbDBMTestCase obj's underlying member method code with example usage: obj.keys_helper(f) and returns: keys