code: def expect_forward(self):
      x, i = self.input_data
      return (x[i],)
  
imports: import unittest
  import warnings
  import numpy
  import pytest
  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
  from chainer.testing import condition
label_desc: Use image node_id 2 for calling the TestTheanoFunctionNonDifferential obj's underlying member method code with example usage: obj.expect_forward() and returns: x