code: def test_gpu(self):
      self.x = cuda.to_gpu(self.x)
      self.r = cuda.to_gpu(self.r)
      self._check()
  
file_path: chainer/tests/chainer_tests/functions_tests/activation_tests/test_rrelu.py
imports: import unittest
  import numpy
  import chainer
  from chainer import cuda
  from chainer import functions
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 4 for calling the TestRReLUR obj's underlying member method code with example usage: obj.test_gpu() without return types