code: def testAttrCopyDelete(self):
      #
      null = self.NULL
  
      def delete_fn(o, k, v):
          assert isinstance(o, MPI.Win)
          assert k == self.keyval
          assert v is win
          MPI.Win.Free(v)
  
      self.keyval = MPI.Win.Create_keyval(delete_fn=delete_fn)
      self.assertNotEqual(self.keyval, MPI.KEYVAL_INVALID)
      #
      win = MPI.Win.Create(MPI.BOTTOM, 1, MPI.INFO_NULL, MPI.COMM_SELF)
      self.obj.Set_attr(self.keyval, win)
      self.assertNotEqual(win, null)
      self.obj.Delete_attr(self.keyval)
      self.assertEqual(win, null)
  
imports: from mpi4py import MPI
  import mpiunittest
label_desc: Use image node_id 2 for calling the TestWinAttr obj's underlying member method code with example usage: obj.testAttrCopyDelete() without return types