code: def __len__(self):
      return len(self.data_idx_order_list)
  
imports: import numpy
  import cv2
  import math
  import os
  import json
  import random
  import traceback
  from paddle.io import Dataset
  from .imaug import transform, create_operators
label_desc: Use image node_id 8 for calling the SimpleDataSet obj's underlying member method code with example usage: obj.__len__() and returns: len