code: def check_multi_gpu_forward(self, train=True):
      # See chainer/chainer#6262
      # NStepBiGRU w/ cudnn and dropout should work on not current device
      msg = None
      rnn = self.rnn.copy("copy")
      rnn.dropout = 0.5
      with cuda.get_device_from_id(1):
          if self.hidden_none:
              h = None
          else:
              h = cuda.to_gpu(self.h)
          xs = [cuda.to_gpu(x) for x in self.xs]
          with testing.assert_warns(DeprecationWarning):
              rnn = rnn.to_gpu()
      with cuda.get_device_from_id(0), chainer.using_config(
          "train", train
      ), chainer.using_config("use_cudnn", "always"):
          try:
              rnn(h, xs)
          except Exception as e:
              msg = e
      assert msg is None
  
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 TestNStepBiGRU obj's underlying member method code with example usage: obj.check_multi_gpu_forward(train) without return types