docstr: Set up the unit test by loading common utilities.
      
docstr_tok: ["Set","up","the","unit","test","by","loading","common","utilities","."]
code: def setUpClass(self):
      """Set up the unit test by loading common utilities."""
      self.err_thresh = 0.15
      self.snr_thresh = 12
      self.psnr_thresh = 30
      self.red_bias = -1
      self.blue_bias = -1
      self.green_bias = -1
      self.image_scale = 2.0 / 255
  
imports: import unittest
  import urllib
  import os
  import tarfile
  import zipfile
  import numpy
  import PIL.Image
  import tensorflow
  from tensorflow.core.framework import graph_pb2
  import tfcoreml
label_desc: Use image node_id 1 for calling the CorrectnessTest obj's underlying member method code with example usage: obj.setUpClass() without return types