code: def check_backward(self, inputs, grad_outputs, backend_config):
      if backend_config.use_cuda:
          inputs = cuda.to_gpu(inputs)
          grad_outputs = cuda.to_gpu(grad_outputs)
  
      with backend_config:
          gradient_check.check_backward(
              slstm.SLSTMGrad(),
              inputs,
              grad_outputs,
              **self.check_backward_options,
          )
  
imports: import unittest
  import numpy
  import six
  from chainer.backends import cuda
  from chainer import functions
  from chainer.functions.rnn import slstm
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import backend
label_desc: Use image node_id 2 for calling the TestSLSTMGrad obj's underlying member method code with example usage: obj.check_backward(inputs, grad_outputs, backend_config) without return types