code: def gen_compares():
      A = np.zeros((100, 100), bool)
      yield A.copy()
  
      A[20:40] = 1
      yield A.copy()
  
      A[:, 20:40] = 1
      yield A.copy()
  
      A[60:80, 60:80] = 1
      yield A.copy()
  
imports: import numpy
  import mahotas.thin
  import pytest
label_desc: Use image node_id 3 for calling a global function with example usage: gen_compares() without return types