code: def __call__(self, x, img_size, scale):
      B, _, H, W = x.shape
      n_anchor = self.n_anchor_base * H * W
  
      rpn_locs = _random_array(self.xp, (B, n_anchor, 4))
      rpn_cls_scores = _random_array(self.xp, (B, n_anchor, 2))
      rois = self.xp.asarray(
          generate_random_bbox(self.n_roi, img_size, 16, min(img_size))
      )
      roi_indices = self.xp.zeros((len(rois),), dtype=np.int32)
      anchor = self.xp.asarray(
          generate_random_bbox(n_anchor, img_size, 16, min(img_size))
      )
      return (
          chainer.Variable(rpn_locs),
          chainer.Variable(rpn_cls_scores),
          rois,
          roi_indices,
          anchor,
      )
  
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 2 for calling the DummyRegionProposalNetwork obj's underlying member method code with example usage: obj.__call__(x, img_size, scale) and returns: chainer,  chainer,  rois,  roi_indices,  anchor