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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def best_prediction(self):
 """The highest value from among the predictions made by the action sets in this match set."""

        if self._best_prediction is None and self._action_sets:
            self._best_prediction = max(
                action_set.prediction
                for action_set in self._action_sets.values()
            )
        return self._best_prediction