code: def _unmap(data, count, index, fill=0):
      # Unmap a subset of item (data) back to the original set of items (of
      # size count)
  
      if len(data.shape) == 1:
          ret = np.empty((count,), dtype=data.dtype)
          ret.fill(fill)
          ret[index] = data
      else:
          ret = np.empty((count,) + data.shape[1:], dtype=data.dtype)
          ret.fill(fill)
          ret[index, :] = data
      return ret
  
file_path: chainercv/chainercv/links/model/faster_rcnn/utils/anchor_target_creator.py
imports: import numpy
  import chainer
  from chainer.backends import cuda
  from chainercv.links.model.faster_rcnn.utils.bbox2loc import bbox2loc
  from chainercv.utils.bbox.bbox_iou import bbox_iou
label_desc: Use image node_id 1 for calling a global function with example usage: _unmap(data, count, index, fill) and returns: ret