code: def test_defaults(self):
      heatmaps = self.heatmaps
      heatmaps_padded = heatmaps.pad(top=1, right=2, bottom=3, left=4)
      assert heatmaps_padded.arr_0to1.shape == (
          2 + (1 + 3),
          2 + (4 + 2),
          1,
      )
      assert np.allclose(
          heatmaps_padded.arr_0to1[:, :, 0],
          np.float32(
              [
                  [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
                  [0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0],
                  [0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0],
                  [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
                  [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
                  [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
              ]
          ),
      )
  
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_pad obj's underlying member method code with example usage: obj.test_defaults() without return types