code: def test_gpu(self):
      self.link.to_gpu()
      self._check(chainer.backends.cuda.cupy)
  
file_path: chainercv/tests/utils_tests/testing_tests/test_constant_stub_link.py
imports: import numpy
  import unittest
  import chainer
  from chainer import testing
  from chainer.testing import attr
  from chainercv.utils import ConstantStubLink
label_desc: Use image node_id 4 for calling the TestConstantStubLink obj's underlying member method code with example usage: obj.test_gpu() without return types