def test_list(self):
"""List of layers"""
s = Stage()
self.assertFalse(s.is_defined())
s += [1, 2]
self.assertTrue(s.is_defined())
def test_value(self):
"""Single layer"""
s = Stage()
self.assertFalse(s.is_defined())
s += 1
self.assertTrue(s.is_defined())
