code: def test_zero_image():
      features = pftas(np.zeros((64, 64), np.uint8))
      assert not np.any(np.isnan(features))
  
file_path: mahotas/mahotas/tests/test_tas.py
imports: import numpy
  from mahotas.features import tas, pftas
  import pytest
label_desc: Use image node_id 4 for calling a global function with example usage: test_zero_image() without return types