code: def test_forward_gpu_multi(self):
      with cuda.get_device_from_id(0):
          with testing.assert_warns(DeprecationWarning):
              self.link.to_gpu()
          c = cuda.to_gpu(self.c)
          h = cuda.to_gpu(self.h)
          x = cuda.to_gpu(self.x)
      with cuda.get_device_from_id(1):
          self.check_forward(c, h, x)
  
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 6 for calling the TestPeephole obj's underlying member method code with example usage: obj.test_forward_gpu_multi() without return types