def METHOD_NAME(self, bounding_boxes, permutation_order):
    boxes, classes = bounding_boxes["boxes"], bounding_boxes["classes"]
    boxes_for_mixup = tf.gather(boxes, permutation_order)
    classes_for_mixup = tf.gather(classes, permutation_order)
    boxes = tf.concat([boxes, boxes_for_mixup], axis=1)
    classes = tf.concat([classes, classes_for_mixup], axis=1)
    return {"boxes": boxes, "classes": classes}