code: def expected_arr(self):
      return np.float32([[8.0, 3.0, -2.0], [9.0, 10.0, 0.5]])
  
imports: from __future__ import print_function, division, absolute_import
  import sys
  import numpy
  import six.moves
  import imgaug
label_desc: Use image node_id 2 for calling the TestHeatmapsOnImage_invert obj's underlying member method code with example usage: obj.expected_arr() and returns: np