new_contents: import numpy as np
  import unittest
  
  import chainer
  from chainer import testing
  from chainer.testing import attr
  
  from chainercv.links.model.ssd import Multibox
  
  
  @testing.parameterize(*testing.product({
      'n_class': [1, 5],
      'aspect_ratios': [((2,),), ((2,), (3, 4), (5,))],
      'batchsize': [1, 2],
  }))
  class TestMultibox(unittest.TestCase):
  
      def setUp(self):
          self.link = Multibox(self.n_class, self.aspect_ratios)
  
          xs = list()
          n_bbox = 0
          for ar in self.aspect_ratios:
              C, H, W = np.random.randint(1, 10, size=3)
              xs.append(
                  np.random.uniform(size=(self.batchsize, C, H, W))
                  .astype(np.float32))
              n_bbox += H * W * (len(ar) + 1) * 2
  
          self.xs = xs
          self.n_bbox = n_bbox
  
      def _check_forward(self, xs):
          loc, conf = self.link(xs)
  
          self.assertIsInstance(loc, chainer.Variable)
          self.assertIsInstance(loc.data, type(xs[0]))
          self.assertEqual(loc.shape, (self.batchsize, self.n_bbox, 4))
          self.assertEqual(loc.dtype, xs[0].dtype)
  
          self.assertIsInstance(conf, chainer.Variable)
          self.assertIsInstance(conf.data, type(xs[0]))
          self.assertEqual(
              conf.shape, (self.batchsize, self.n_bbox, self.n_class))
          self.assertEqual(conf.dtype, xs[0].dtype)
  
      def test_forward_cpu(self):
          self._check_forward(self.xs)
  
      @attr.gpu
      def test_forward_gpu(self):
          self.link.to_gpu()
          self._check_forward(list(map(chainer.cuda.to_gpu, self.xs)))
  
  
  testing.run_module(__name__, __file__)
  
subject: add test of Multibox