code: def __len__(self):
      return len(self.data_infos)
  
imports: from ppdet.core.workspace import register, serializable
  import cv2
  import os
  import tarfile
  import numpy
  import os.path
  from ppdet.data.source.dataset import DetDataset
  from imgaug.augmentables.lines import LineStringsOnImage
  from imgaug.augmentables.segmaps import SegmentationMapsOnImage
  from ppdet.data.culane_utils import lane_to_linestrings
  import pickle
  from ppdet.utils.logger import setup_logger
  from .dataset import DetDataset, _make_dataset, _is_valid_file
  from ppdet.utils.download import download_dataset
label_desc: Use image node_id 2 for calling the CULaneDataSet obj's underlying member method code with example usage: obj.__len__() and returns: len