code: def forward(self, x):
      n_sample = x.shape[0]
      n_dims = (32, 16, 8)
      return [
          chainer.Variable(
              _random_array(self.xp, (n_sample, n_dim, grid, grid))
          )
          for grid, n_dim in zip(self.grids, n_dims)
      ]
  
imports: import numpy
  import unittest
  import chainer
  from chainer import testing
  from chainer.testing import attr
  from chainercv.links.model.ssd import Multibox
  from chainercv.links.model.ssd import SSD
  from chainercv.utils import assert_is_detection_link
label_desc: Use image node_id 1 for calling the DummyExtractor obj's underlying member method code with example usage: obj.forward(x) and returns: unknown