code: def test_predict_gpu(self):
      self.link.to_gpu()
      assert_is_detection_link(self.link, self.n_class - 1)
  
imports: import numpy
  import unittest
  import chainer
  from chainer import testing
  from chainer.testing import attr
  from chainercv.links.model.light_head_rcnn import LightHeadRCNN
  from chainercv.utils import assert_is_detection_link
  from chainercv.utils import generate_random_bbox
label_desc: Use image node_id 6 for calling the TestLightHeadRCNN obj's underlying member method code with example usage: obj.test_predict_gpu() without return types