Comment Comment by jdmichal You've "invented" interlocking railway semaphores, after which the computer science concept was named.https://en.wikipedia.org/wiki/Railway_semaphore_signalhttps://en.wikipedia.org/wiki/Interlocking parent jdmichal 12 days ago
https://en.wikipedia.org/wiki/Railway_semaphore_signal
https://en.wikipedia.org/wiki/Interlocking