code: def iou(box1, box2):
          
          int_box = Box.intersection_box(box1, box2)
          int_area = int_box.area()
          union_area = box1.area() + box2.area() - int_area
  
          result = 0.0
          if union_area > 0:
              result = float(int_area) / float(union_area)
  
          return result
docs: Find intersection over union-area for given two boxes.
              It the ratio of intersection-area / union-area
  
          :param box1: Box object 1
          :param box2: Box object 2
          :return: Intersection-over-union value