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opposite traffic lights sketch

A reference clafer is a clafer whose value is another clafer.

We can define the opposite traffic light as follows

abstract TrafficLight
opposite -> TrafficLight
xor signal
stop
[ opposite.signal.stop ]
proceed
[ opposite.signal.proceed ]
EastWest : TrafficLight
[ opposite = WestEast ]
WestEast : TrafficLight
[ opposite = EastWest ]

Back to the conclusion of Part III