code: def __len__(self):
      return self.data_idx_order_list.shape[0]
  
imports: import numpy
  import os
  from paddle.io import Dataset
  import lmdb
  import cv2
  import string
  import six
  import pickle
  from PIL import Image
  from .imaug import transform, create_operators
label_desc: Use image node_id 5 for calling the LMDBDataSetTableMaster obj's underlying member method code with example usage: obj.__len__() and returns: self