code: def _forward(self, link, x):
      return link(x)
  
imports: import unittest
  import numpy
  import chainer
  from chainer import backend
  from chainer.backends import cuda
  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 TestZoneoutlstm obj's underlying member method code with example usage: obj._forward(link, x) and returns: link