code: def test_thin():
      A = np.zeros((100, 100), bool)
      A[20:40] = 1
      W = mahotas.thin(A)
      assert mahotas.erode(W).sum() == 0
      assert (W & A).sum() == W.sum()
  
imports: import numpy
  import mahotas.thin
  import pytest
label_desc: Use image node_id 2 for calling a global function with example usage: test_thin() without return types