code: def iou(boxes1, boxes2):
      """Computes pairwise intersection-over-union between box collections.
  
      Args:
        boxes1: a numpy array with shape [N, 4] holding N boxes.
        boxes2: a numpy array with shape [M, 4] holding N boxes.
  
      Returns:
        a numpy array with shape [N, M] representing pairwise iou scores.
      """
      intersect = intersection(boxes1, boxes2)
      area1 = area(boxes1)
      area2 = area(boxes2)
      union = (
          np.expand_dims(area1, axis=1)
          + np.expand_dims(area2, axis=0)
          - intersect
      )
      return intersect / union
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: iou(boxes1, boxes2) and returns: unknown