code: def test_dummy_limits(self):
      b, e = dummy_limits(self.d1)
      assert_equal(b, np.array([0, 4, 8]))
      assert_equal(e, np.array([4, 8, 12]))
  
imports: from numpy.testing import assert_equal
  import numpy
label_desc: Use image node_id 4 for calling the TestContrastTools obj's underlying member method code with example usage: obj.test_dummy_limits() without return types