from tensorflow.python.platform import gfile

      self.assertTrue(gfile.Exists(s2))

      s3 = save.save(sess, os.path.join(save_dir, "s3"))
      self.assertEqual([s2, s3], save.last_checkpoints)
      self.assertFalse(gfile.Exists(s1))
      self.assertTrue(gfile.Exists(s2))
      self.assertTrue(gfile.Exists(s3))

      # Create a second helper, identical to the first.
      save2 = tf.train.Saver(saver_def=save.as_saver_def())
      save2.set_last_checkpoints(save.last_checkpoints)

