code: def test_batch_size(self):
      # batch size doesn't change the numpy interface
      sampler = ImageWindowDataset(reader=get_3d_reader(), batch_size=2)
      self.assert_tf_window(sampler)
      self.assert_window(sampler())
  
imports: from __future__ import absolute_import, print_function
  import os
  import numpy
  import tensorflow
  from niftynet.engine.image_window_dataset import ImageWindowDataset
  from niftynet.io.image_reader import ImageReader
  from tests.niftynet_testcase import NiftyNetTestCase
label_desc: Use image node_id 4 for calling the ImageWindowDataset_3D_Test obj's underlying member method code with example usage: obj.test_batch_size() without return types