code: def accumulate(self):
      self.cls_summary_list = []
      for row in range(self.num_classes):
          seqs_cls_df = pd.concat(self.seqs_overall[row])
          seqs_cls_summary = seqs_overall_metrics(seqs_cls_df)
          cls_summary_overall = seqs_cls_summary.iloc[-1:].copy()
          cls_summary_overall.rename(
              index={"overall_calc": "overall_calc_{}".format(row)},
              inplace=True,
          )
          self.cls_summary_list.append(cls_summary_overall)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  import copy
  import sys
  import math
  from collections import defaultdict
  import numpy
  import pandas
  from .metrics import Metric
  from ppdet.utils.logger import setup_logger
label_desc: Use image node_id 4 for calling the MCMOTMetric obj's underlying member method code with example usage: obj.accumulate() without return types