def add_final_state(self, f):

        """
        :param f: int , the state qi to be added to F, epsilon is
        conventionally defined as the last node (q_|S|)
        """
        if f not in self.Q:
            LOG.error("The specified value is invalid, f must be a member of Q")
            raise InputError("The specified value is invalid, f must be a member of Q")

        self.F.add(f)