code: def _box_iou(a, b):
      return _box_intersection(a, b) / _box_union(a, b)
  
imports: from __future__ import division
  import math
  from collections import namedtuple
  from functools import cmp_to_key
  import numpy
label_desc: Use image node_id 6 for calling a global function with example usage: _box_iou(a, b) and returns: unknown