code: def check_to_cpu_to_gpu(self, c, h):
      self.link.c = c
      self.link.h = h
      with testing.assert_warns(DeprecationWarning):
          self.link.to_gpu()
      self.assertIs(self.link.xp, cuda.cupy)
      self.assertIsInstance(self.link.c.data, self.link.xp.ndarray)
      self.assertIsInstance(self.link.h.data, self.link.xp.ndarray)
      with testing.assert_warns(DeprecationWarning):
          self.link.to_gpu()
      self.assertIs(self.link.xp, cuda.cupy)
      self.assertIsInstance(self.link.c.data, self.link.xp.ndarray)
      self.assertIsInstance(self.link.h.data, self.link.xp.ndarray)
      with testing.assert_warns(DeprecationWarning):
          self.link.to_cpu()
      self.assertIs(self.link.xp, numpy)
      self.assertIsInstance(self.link.c.data, self.link.xp.ndarray)
      self.assertIsInstance(self.link.h.data, self.link.xp.ndarray)
      with testing.assert_warns(DeprecationWarning):
          self.link.to_gpu()
      self.assertIs(self.link.xp, cuda.cupy)
      self.assertIsInstance(self.link.c.data, self.link.xp.ndarray)
      self.assertIsInstance(self.link.h.data, self.link.xp.ndarray)
  
imports: import unittest
  import numpy
  import chainer
  from chainer import backend
  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 5 for calling the TestZoneoutToCPUToGPU obj's underlying member method code with example usage: obj.check_to_cpu_to_gpu(c, h) without return types