def test_should_be_able_to_add_existing(self):
     s = OrderedSet([1, 2, 3])
     s.add(2)
     assert list(s) == [1, 2, 3]
 def test_should_be_able_to_add_new(self):
     s = OrderedSet([1, 2, 3])
     s.add(4)
     assert list(s) == [1, 2, 3, 4]