code: def test_add_done_callback_simple(self):
      callback_result = False
  
      def callback(fut):
          nonlocal callback_result
          fut.wait()
          callback_result = True
  
      fut = Future[torch.Tensor]()
      fut.add_done_callback(callback)
  
      self.assertFalse(callback_result)
      fut.set_result(torch.ones(2, 2))
      self.assertEqual(fut.wait(), torch.ones(2, 2))
      self.assertTrue(callback_result)
  
imports: import threading
  import time
  import torch
  import unittest
  from torch.futures import Future
  from torch.testing._internal.common_utils import IS_WINDOWS, TestCase, TemporaryFileName, run_tests
  from typing import TypeVar
label_desc: Use image node_id 15 for calling the TestFuture obj's underlying member method code with example usage: obj.test_add_done_callback_simple() without return types