code: def test_forward_cpu(self):
      self._check_forward(self.xs)
  
file_path: chainercv/tests/links_tests/model_tests/ssd_tests/test_multibox.py
imports: import numpy
  import unittest
  import chainer
  from chainer import testing
  from chainer.testing import attr
  from chainercv.links.model.ssd import Multibox
label_desc: Use image node_id 3 for calling the TestMultibox obj's underlying member method code with example usage: obj.test_forward_cpu() without return types