code: def normalize(image, label):
      """Convert `image` from [0, 255] -> [-0.5, 0.5] floats."""
      image = tf.cast(image, tf.float32) * (1.0 / 255) - 0.5
      return image, label
  
file_path: attributionpriors/attributionpriors/mnist/mnist_reader.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import argparse
  import os.path
  import sys
  import time
  import math
  import tensorflow
  from tensorflow.examples.tutorials.mnist import mnist
label_desc: Use image node_id 3 for calling a global function with example usage: normalize(image, label) and returns: image,  label