code: def test_fileclosed(self):
      try:
          with open(os_helper.TESTFN, "w", encoding="utf-8") as f:
              self.assertIs(f.closed, False)
          self.assertIs(f.closed, True)
      finally:
          os.remove(os_helper.TESTFN)
  
imports: import unittest
  from test.support import os_helper
  import os
label_desc: Use image node_id 18 for calling the BoolTest obj's underlying member method code with example usage: obj.test_fileclosed() without return types