code: def test_generate_mean(self):
      zeros = bytearray(100)
      fifties = bytearray([50] * 100)
      hundreds = bytearray([100] * 100)
      img1 = image.Image(
          _image_data=zeros,
          _channels=1,
          _height=1,
          _width=100,
          _image_data_size=100,
          _format_enum=2,
      )  # format 2 is RAW
      img2 = image.Image(
          _image_data=hundreds,
          _channels=1,
          _height=1,
          _width=100,
          _image_data_size=100,
          _format_enum=2,
      )
      img3 = image.Image(
          _image_data=fifties,
          _channels=1,
          _height=1,
          _width=100,
          _image_data_size=100,
          _format_enum=2,
      )
  
      sa = SArray([img1, img2])
      average = sa.mean()
      sa2 = SArray([img2, img2])
      average2 = sa2.mean()
  
      self.assertEqual(average, img3)
      self.assertEqual(average2, img2)
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  import array
  import unittest
  from PIL import Image
  import os
  from ..data_structures import image
  from ..None import SArray
  from ..toolkits.image_analysis import image_analysis
  from ..toolkits._main import ToolkitError
  from .._deps import numpy, HAS_NUMPY
label_desc: Use image node_id 11 for calling the ImageClassTest obj's underlying member method code with example usage: obj.test_generate_mean() without return types