code: def test_subm_out():
      np.random.seed(32)
      for j in range(8):
          s = (128, 256)
          a = np.random.randint(0, 255, size=s)
          b = np.random.randint(0, 255, size=s)
  
          c = subm(a, b)
          assert c is not a
          assert c is not b
          assert not np.all(c == a)
  
          c = subm(a, b, out=a)
          assert c is a
          assert c is not b
          assert np.all(c == a)
  
imports: import mahotas
  import numpy
  from mahotas.morph import get_structuring_elem, subm, tophat_open, tophat_close
  import pytest
label_desc: Use image node_id 12 for calling a global function with example usage: test_subm_out() without return types