code: def accumulate(self):
      loss_lines = [[], [], [], []]
      for idx, pred in enumerate(self.predictions):
          output_dir = os.path.join(
              self.output_eval, os.path.dirname(self.img_names[idx])
          )
          output_filename = (
              os.path.basename(self.img_names[idx])[:-3] + "lines.txt"
          )
          os.makedirs(output_dir, exist_ok=True)
          output = self.get_prediction_string(pred)
  
          # store loss lines
          lanes = self.lanes[idx]
          if len(lanes) - len(pred) in [1, 2, 3, 4]:
              loss_lines[len(lanes) - len(pred) - 1].append(
                  self.img_names[idx]
              )
  
          with open(
              os.path.join(output_dir, output_filename), "w"
          ) as out_file:
              out_file.write(output)
  
      for i, names in enumerate(loss_lines):
          with open(
              os.path.join(
                  output_dir, "loss_{}_lines.txt".format(i + 1)
              ),
              "w",
          ) as f:
              for name in names:
                  f.write(name + "\n")
  
      for cate, cate_file in CATEGORYS.items():
          result = eval_predictions(
              self.output_eval,
              self.dataset_dir,
              os.path.join(self.dataset_dir, cate_file),
              iou_thresholds=[0.5],
              official=True,
          )
  
      result = eval_predictions(
          self.output_eval,
          self.dataset_dir,
          self.list_path,
          iou_thresholds=np.linspace(0.5, 0.95, 10),
          official=True,
      )
      self.eval_results["F1@50"] = result[0.5]["F1"]
      self.eval_results["result"] = result
  
imports: import os
  import cv2
  import numpy
  import os.path
  from functools import partial
  from .metrics import Metric
  from scipy.interpolate import splprep, splev
  from scipy.optimize import linear_sum_assignment
  from shapely.geometry import LineString, Polygon
  from ppdet.utils.logger import setup_logger
label_desc: Use image node_id 4 for calling the CULaneMetric obj's underlying member method code with example usage: obj.accumulate() without return types