code: def assert_good_external_format(expl, overlay):
      """
      Check properties of the formatted heatmap over the original image,
      using external properties of the image,
      such as dimensions, mode, type.
      """
      original = expl.image
      # check external properties
      assert isinstance(overlay, Image.Image)
      assert overlay.width == original.width
      assert overlay.height == original.height
      assert overlay.mode == "RGBA"
  
file_path: eli5/tests/test_keras_integration.py
imports: from __future__ import print_function
  import pytest
  import numpy
  from PIL import Image
  from keras.applications import mobilenet_v2
  from keras.models import Sequential
  import eli5
  from eli5.base import Explanation
  from eli5 import format_as_image
  from eli5.formatters.image import expand_heatmap
  from .utils_image import assert_pixel_by_pixel_equal
label_desc: Use image node_id 3 for calling a global function with example usage: assert_good_external_format(expl, overlay) without return types