def METHOD_NAME(self):
    # for example, Camembert overwrites <unk>, <s> and </s>
    dict_file = io.StringIO(
        "<unk> 999\n" "<s> 999\n" "</s> 999\n" ", 999\n" "▁de 999\n"
    )
    d = Dictionary()
    with self.assertRaisesRegex(RuntimeError, "Duplicate"):
        d.add_from_file(dict_file)