code: def best_actions(self):
          
          if self._best_actions is None:
              best_prediction = self.best_prediction
              self._best_actions = tuple(
                  action
                  for action, action_set in self._action_sets.items()
                  if action_set.prediction == best_prediction
              )
          return self._best_actions
docs: A tuple containing the actions whose action sets have the best
          prediction.