code: def test_extract_square(self):
      hm = iadata.quokka_heatmap(extract="square")
      assert hm.shape == (643, 643, 3)
      assert hm.arr_0to1.shape == (643, 643, 1)
      # TODO this value is 0.48026073 in python 2.7, while 0.48026952 in
      #      3.7 -- why?
      assert np.allclose(
          np.average(hm.arr_0to1), 0.48026952, rtol=0, atol=1e-3
      )
  
imports: from __future__ import print_function, division, absolute_import
  import warnings
  import sys
  import numpy
  import imgaug
  import imgaug.data
  from imgaug.data import _quokka_normalize_extract, _compute_resized_shape
label_desc: Use image node_id 2 for calling the Test_quokka_heatmap obj's underlying member method code with example usage: obj.test_extract_square() without return types