code: def test_close_exception(self):
      ds = self._dataset(["ascii_1.txt", "ascii_1.txt", "ascii_1.txt"])
      assert not ds._fps[0].closed
      assert not ds._fps[1].closed
      assert not ds._fps[2].closed
      ds._fps[1] = None
      with self.assertRaises(AttributeError):
          ds.close()
      assert ds._fps[0].closed
      assert ds._fps[2].closed
  
imports: from __future__ import unicode_literals
  import os
  import pickle
  import unittest
  import six
  from chainer import datasets
  from chainer import testing
label_desc: Use image node_id 4 for calling the TestTextDataset obj's underlying member method code with example usage: obj.test_close_exception() without return types