code: def test_grad(self, mode):
      # no grad for GpuCumOp
      pass
  
imports: from __future__ import absolute_import, print_function, division
  from functools import partial
  from itertools import product
  import numpy
  from six.moves import xrange
  from theano import tensor
  import theano
  import theano.tensor.tests.test_extra_ops
  from theano.tensor.extra_ops import CumOp
  from theano.tests.unittest_tools import SkipTest
  from theano.tests import unittest_tools
  from .config import mode_with_gpu, test_ctx_name
  from ..extra_ops import GpuCumOp
  from ..type import get_context
label_desc: Use image node_id 4 for calling the TestGpuCumOp obj's underlying member method code with example usage: obj.test_grad(mode) without return types