code: def _compare_slow(img):
      for n in (4, 8):
          assert np.all(_slow_bwperim(img, n) == bwperim(img, n))
  
imports: from mahotas import bwperim
  import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: _compare_slow(img) without return types