code: def bbox2roi(self, bbox_list):
      rois_list = []
      rois_num = []
      for img_id, bboxes in enumerate(bbox_list):
          rois_num.append(bboxes.shape[0])
          rois_list.append(bboxes)
      rois = paddle.concat(rois_list, 0)
      rois_num = paddle.to_tensor(rois_num, dtype="int32")
      return rois, rois_num
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import paddle
  from paddle import nn
  import numpy
  import cv2
label_desc: Use image node_id 2 for calling the Kie_backbone obj's underlying member method code with example usage: obj.bbox2roi(bbox_list) and returns: rois,  rois_num