code: def test_forward_gpu(self):
      inputs = [cuda.to_gpu(x) for x in self.input_data]
      self.check_forward(inputs)
  
imports: import unittest
  import warnings
  import numpy
  import pytest
  import chainer
  from chainer.backends import cuda
  from chainer import gradient_check
  from chainer import links
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import condition
label_desc: Use image node_id 6 for calling the TheanoFunctionTestBase obj's underlying member method code with example usage: obj.test_forward_gpu() without return types