code: def normalize(input_image, input_mask):
      input_image = tf.cast(input_image, tf.float32) / 128.0 - 1
      input_mask -= 1
      return input_image, input_mask
  
file_path: TensorFlowOnSpark/examples/segmentation/segmentation_dist.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from tensorflow_examples.models.pix2pix import pix2pix
  import json
  import os
  import tensorflow_datasets
  import tensorflow
label_desc: Use image node_id 1 for calling a global function with example usage: normalize(input_image, input_mask) and returns: input_image,  input_mask