code: def forward_expected(self, inputs):
      (x,) = inputs
      y = _sigmoid(x)
      y = utils.force_array(y)
      return (y,)
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import functions
  from chainer import testing
  from chainer.testing import attr
  from chainer import utils
label_desc: Use image node_id 3 for calling the TestSigmoid obj's underlying member method code with example usage: obj.forward_expected(inputs) and returns: y