code: def test_write_contains(self):
      with contextlib.closing(dumbdbm.open(_fname)) as f:
          f[b"1"] = b"hello"
          self.assertIn(b"1", f)
  
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 7 for calling the DumbDBMTestCase obj's underlying member method code with example usage: obj.test_write_contains() without return types