code: def test_forward_nonzero_gpu_test(self):
      # Issue #5347
      # to_gpu should work without setting the current device
      with testing.assert_warns(DeprecationWarning):
          self.rnn.to_gpu(1)
      with chainer.using_config(
          "use_cudnn", "always"
      ), chainer.using_config("train", False):
          self.check_forward(
              cuda.to_gpu(self.h, 1),
              cuda.to_gpu(self.c, 1),
              [cuda.to_gpu(x, 1) for x in self.xs],
          )
  
imports: import unittest
  import numpy
  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
label_desc: Use image node_id 7 for calling the TestNStepLSTM obj's underlying member method code with example usage: obj.test_forward_nonzero_gpu_test() without return types