code: def __len__(self):
      return len(self.lines)
  
imports: import argparse
  import os
  import pickle
  import timeit
  import cv2
  import mxnet
  import numpy
  import pandas
  import prettytable
  import skimage.transform
  from sklearn.metrics import roc_curve
  from sklearn.preprocessing import normalize
  from onnx_helper import ArcFaceORT
label_desc: Use image node_id 2 for calling the AlignedDataSet obj's underlying member method code with example usage: obj.__len__() and returns: len