code: def test_gpu(self):
      self._test(gpu=0)
  
file_path: chainerrl/tests/optimizer_tests/test_nonbias_weight_decay.py
imports: import unittest
  import chainer
  import chainer.links
  from chainer import testing
  import numpy
  import chainerrl
label_desc: Use image node_id 3 for calling the TestNonbiasWeightDecay obj's underlying member method code with example usage: obj.test_gpu() without return types