code: def test_zero_image(method):
      A = np.zeros((16, 16), np.uint8)
      assert method(A, ignore_zeros=0) == 0
      assert method(A, ignore_zeros=1) == 0
  
file_path: mahotas/mahotas/tests/test_thresholding.py
imports: import numpy
  from mahotas.thresholding import otsu, rc, bernsen, gbernsen
  from mahotas.histogram import fullhistogram
  import pytest
label_desc: Use image node_id 6 for calling a global function with example usage: test_zero_image(method) without return types