code: def heatmaps_arr(self):
      return np.float32([[0.0, 5.0, 10.0], [-1.0, -2.0, 7.5]])
  
imports: from __future__ import print_function, division, absolute_import
  import sys
  import numpy
  import six.moves
  import imgaug
label_desc: Use image node_id 1 for calling the TestHeatmapsOnImage_invert obj's underlying member method code with example usage: obj.heatmaps_arr() and returns: np