code: def forward(self, inputs):
      self.retain_inputs((0,))
      return (inputs[0],)
  
imports: import re
  import unittest
  import numpy
  import six
  import chainer
  from chainer.backends import cuda
  from chainer import function_hooks
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 1 for calling the DummyFunction obj's underlying member method code with example usage: obj.forward(inputs) and returns: inputs