code: def _expand_bbox(bbox, scale):
      """Expand an array of boxes by a given scale."""
      xp = chainer.backends.cuda.get_array_module(bbox)
  
      h_half = (bbox[:, 2] - bbox[:, 0]) * 0.5
      w_half = (bbox[:, 3] - bbox[:, 1]) * 0.5
      y_c = (bbox[:, 2] + bbox[:, 0]) * 0.5
      x_c = (bbox[:, 3] + bbox[:, 1]) * 0.5
  
      h_half *= scale
      w_half *= scale
  
      expanded_bbox = xp.zeros(bbox.shape)
      expanded_bbox[:, 0] = y_c - h_half
      expanded_bbox[:, 1] = x_c - w_half
      expanded_bbox[:, 2] = y_c + h_half
      expanded_bbox[:, 3] = x_c + w_half
  
      return expanded_bbox
  
file_path: chainercv/chainercv/links/model/fpn/mask_utils.py
imports: from __future__ import division
  import numpy
  import chainer
  from chainercv import transforms
label_desc: Use image node_id 4 for calling a global function with example usage: _expand_bbox(bbox, scale) and returns: expanded_bbox