class_docstr: Convert between text-label and text-index 
code: def _metric(self, pred_relations, label):
      return pred_relations, label[-1], label[-2]
  
file_path: PaddleOCR/ppocr/postprocess/vqa_token_re_layoutlm_postprocess.py
imports: import paddle
label_desc: Use image node_id 3 for calling the VQAReTokenLayoutLMPostProcess obj's underlying member method code with example usage: obj._metric(pred_relations, label) and returns: pred_relations,  label,  label