def add_eval(self, agent, e, fr=None):
        """Add or change agent's evaluation of the artifact with given framing
        information.

        :param agent: Name of the agent which did the evaluation.
        :param float e: Evaluation for the artifact.
        :param object fr: Framing information for the evaluation.
        """
        self._evals[agent.name] = e
        self._framings[agent.name] = fr