code: def strel_worker(self, fn, func):
      matlab_masks = np.load(fetch(fn))
      k = 0
      for arrname in sorted(matlab_masks):
          expected_mask = matlab_masks[arrname]
          actual_mask = func(k)
          if expected_mask.shape == (1,):
              expected_mask = expected_mask[:, np.newaxis]
          assert_equal(expected_mask, actual_mask)
          k = k + 1
  
imports: import numpy
  import pytest
  from numpy.testing import assert_equal
  from skimage._shared.testing import fetch
  from skimage.morphology import footprints
label_desc: Use image node_id 4 for calling the TestFootprints obj's underlying member method code with example usage: obj.strel_worker(fn, func) without return types