code: def add_eval(self, agent, e, fr=None):
          
          self._evals[agent.name] = e
          self._framings[agent.name] = fr
docs: 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.