code: def test_forward_gpu(self):
      self.check_forward(
          cuda.to_gpu(self.x), cuda.to_gpu(self.W), cuda.to_gpu(self.b)
      )
  
imports: import unittest
  import numpy
  from chainer.backends import cuda
  from chainer import functions
  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 5 for calling the TestDepthwiseConvolution2DFunction obj's underlying member method code with example usage: obj.test_forward_gpu() without return types