def test_append(self):
    c = Collection([3, 4, 5])
    c.append(6)
    self.assertEqual([3, 4, 5, 6], c.all())
def test_append(self):
    c = Collection([3, 4, 5])
    c.append(6)
    self.assertEqual([3, 4, 5, 6], c.all())