code: def test_backward_gpu(self):
      self.check_backward(
          cuda.to_gpu(self.x),
          cuda.to_gpu(self.W),
          cuda.to_gpu(self.b),
          cuda.to_gpu(self.gy),
      )
  
imports: import unittest
  import numpy
  from six import moves
  from chainer import cuda
  from chainer.functions.connection import convolution_2d
  from chainer.functions.connection import local_convolution_2d
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import condition
label_desc: Use image node_id 10 for calling the TestLocalConvolution2DFunction obj's underlying member method code with example usage: obj.test_backward_gpu() without return types