code: def test_call_cpu(self):
      self._check_call(self.x, self.img_size, self.scales)
  
file_path: chainercv/tests/links_tests/model_tests/faster_rcnn_tests/test_region_proposal_network.py
imports: import numpy
  import unittest
  import chainer
  from chainer.backends import cuda
  from chainer import testing
  from chainer.testing import attr
  from chainercv.links.model.faster_rcnn import RegionProposalNetwork
label_desc: Use image node_id 3 for calling the TestRegionProposalNetwork obj's underlying member method code with example usage: obj.test_call_cpu() without return types