def outputForInput(self, inState, inputSymbol):
        """
        A 2-tuple of (outState, outputSymbols) for inputSymbol.
        """
        for (anInState, anInputSymbol,
             outState, outputSymbols) in self._transitions:
            if (inState, inputSymbol) == (anInState, anInputSymbol):
                return (outState, list(outputSymbols))
        raise NoTransition(state=inState, symbol=inputSymbol)