code: def bbox_iou(bbox_a, bbox_b, offset=0):
      """Calculate Intersection-Over-Union(IOU) of two bounding boxes.
  
      Parameters
      ----------
      bbox_a : numpy.ndarray
          An ndarray with shape :math:`(N, 4)`.
      bbox_b : numpy.ndarray
          An ndarray with shape :math:`(M, 4)`.
      offset : float or int, default is 0
          The ``offset`` is used to control the whether the width(or height) is computed as
          (right - left + ``offset``).
          Note that the offset must be 0 for normalized bboxes, whose ranges are in ``[0, 1]``.
  
      Returns
      -------
      numpy.ndarray
          An ndarray with shape :math:`(N, M)` indicates IOU between each pairs of
          bounding boxes in `bbox_a` and `bbox_b`.
  
      """
      if bbox_a.shape[1] < 4 or bbox_b.shape[1] < 4:
          raise IndexError(
              "Bounding boxes axis 1 must have at least length 4"
          )
  
      tl = np.maximum(bbox_a[:, None, :2], bbox_b[:, :2])
      br = np.minimum(bbox_a[:, None, 2:4], bbox_b[:, 2:4])
  
      area_i = np.prod(br - tl + offset, axis=2) * (tl < br).all(axis=2)
      area_a = np.prod(bbox_a[:, 2:4] - bbox_a[:, :2] + offset, axis=1)
      area_b = np.prod(bbox_b[:, 2:4] - bbox_b[:, :2] + offset, axis=1)
      return area_i / (area_a[:, None] + area_b - area_i)
  
imports: from __future__ import division
  import numpy
label_desc: Use image node_id 1 for calling a global function with example usage: bbox_iou(bbox_a, bbox_b, offset) and returns: unknown