class_docstr: Base Data Geneartor
class_docstr_tok: ["Base","Data","Geneartor"]
code: def __len__(self):
      return len(self.line_examples)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  from __future__ import absolute_import
  import os
  import sys
  import six
  from io import open
  from collections import namedtuple
  import numpy
  import tqdm
  import paddle
  from pgl.utils import mp_reader
  import collections
  import time
  from pgl.utils.logger import log
  import traceback
label_desc: Use image node_id 4 for calling the BaseDataGenerator obj's underlying member method code with example usage: obj.__len__() and returns: len