class_docstr: Convert between text-label and text-index 
code: def _infer(self, pred_relations, *args, **kwargs):
      ser_results = kwargs["ser_results"]
      entity_idx_dict_batch = kwargs["entity_idx_dict_batch"]
  
      # merge relations and ocr info
      results = []
      for pred_relation, ser_result, entity_idx_dict in zip(
          pred_relations, ser_results, entity_idx_dict_batch
      ):
          result = []
          used_tail_id = []
          for relation in pred_relation:
              if relation["tail_id"] in used_tail_id:
                  continue
              used_tail_id.append(relation["tail_id"])
              ocr_info_head = ser_result[
                  entity_idx_dict[relation["head_id"]]
              ]
              ocr_info_tail = ser_result[
                  entity_idx_dict[relation["tail_id"]]
              ]
              result.append((ocr_info_head, ocr_info_tail))
          results.append(result)
      return results
  
file_path: PaddleOCR/ppocr/postprocess/vqa_token_re_layoutlm_postprocess.py
imports: import paddle
label_desc: Use image node_id 4 for calling the VQAReTokenLayoutLMPostProcess obj's underlying member method code with example usage: obj._infer(pred_relations) and returns: results