code: def test_gpu(self):
      self._test(0)
  
imports: import unittest
  import chainer
  from chainer import testing
  from chainer.testing import condition
  import numpy
  import scipy.stats
  from chainerrl import distribution
label_desc: Use image node_id 3 for calling the TestSampleDiscreteActions obj's underlying member method code with example usage: obj.test_gpu() without return types