code: def test_verify_grad(self):
      def ctc_op_functor(labels, in_lengths):
          def wrapper(acts):
              # Create auxiliary symbolic variables
              t_activation_times = theano.shared(
                  in_lengths, name="activation_times"
              )
              t_labels = theano.shared(labels, name="labels")
              return gpu_ctc(acts, t_labels, t_activation_times)
  
          return wrapper
  
      activations, labels, activation_times = setup_grad_case()
  
      ctc_op = ctc_op_functor(labels, activation_times)
  
      utt.verify_grad(ctc_op, [activations], mode=mode_with_gpu)
  
imports: from __future__ import division, absolute_import, print_function
  import unittest
  import numpy
  import theano
  import theano.tensor
  from theano.tests import unittest_tools
  import theano.gpuarray
  from theano.gpuarray.ctc import gpu_ctc, GpuConnectionistTemporalClassification
  from theano.tensor.nnet.ctc import ctc, ctc_available, ConnectionistTemporalClassification
  from theano.tensor.nnet.tests.test_ctc import setup_torch_case, setup_ctc_case, setup_grad_case
  from .config import mode_with_gpu, mode_without_gpu
label_desc: Use image node_id 13 for calling the TestCTC obj's underlying member method code with example usage: obj.test_verify_grad() and returns: wrapper, gpu_ctc