code: def sigmoid(self, x):
      half = x.dtype.type(0.5)
      return numpy.tanh(x * half) * half + half
  
file_path: chainer/tests/chainer_tests/links_tests/connection_tests/test_highway.py
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import functions
  from chainer import gradient_check
  from chainer import links
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 2 for calling the TestHighway obj's underlying member method code with example usage: obj.sigmoid(x) and returns: unknown