code: def test_border_grad_gpu(self):
      self.check_border_grad(
          cuda.to_gpu(self.x), cuda.to_gpu(self.expected)
      )
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 4 for calling the TestClipBorderGrad obj's underlying member method code with example usage: obj.test_border_grad_gpu() without return types