code: def test_signed():
      A = np.array([0, 0, 1, 1, 1, 0, 0, 0], dtype=np.int32)
      B = np.array([0, 1, 0])
      assert np.min(mahotas.erode(A, B)) == -1
  
file_path: mahotas/mahotas/tests/test_dilate_erode.py
imports: import numpy
  import mahotas
  import mahotas
label_desc: Use image node_id 4 for calling a global function with example usage: test_signed() without return types