def __call__(cls, *args, **kwds):
    """Instantiate cls after preprocessing its token definitions."""
    if '_tokens' not in cls.__dict__:
        cls._all_tokens = {}
        cls._tmpname = 0
        if hasattr(cls, 'token_variants') and cls.token_variants:
            pass
        else:
            cls._tokens = cls.process_tokendef('', cls.get_tokendefs())
    return type.__call__(cls, *args, **kwds)
