code: def _test_correctness(self, args, aff, expected_value):
      grid_warper = AffineGridWarperLayer(**args)
      computed_grid = grid_warper(aff)
      with self.cached_session() as sess:
          output_val = sess.run(computed_grid)
          self.assertAllClose(expected_value, output_val)
  
imports: from __future__ import absolute_import, print_function, division
  import numpy
  import tensorflow
  from niftynet.layer.grid_warper import AffineGridWarperLayer
  from niftynet.layer.grid_warper import AffineWarpConstraints
  from niftynet.layer.grid_warper import _create_affine_features
  from tests.niftynet_testcase import NiftyNetTestCase
label_desc: Use image node_id 1 for calling the AffineGridWarperLayerTest obj's underlying member method code with example usage: obj._test_correctness(args, aff, expected_value) without return types