Set values in constant

def add(self, name, attr=None, value=None):
        "Set values in constant"

        if isinstance(name, tuple) or isinstance(name, list):
            name, attr, value = self.__set_iter_value(name)

        if attr is None:
            attr = name

        if value is None:
            value = attr

        self.__data += (self.get_const_string(name=name, value=value),)
        # set attribute as slugfiy
        self.__dict__[s_attr(attr)] = self.__data[-1]