A deadman timer that expires unless fed often enough.
Creates a watchdog that expires after timeout without being fed; a timeout that is not a number is taken as 0.
timeout
Whether the watchdog has expired.
Feeds the watchdog, restarting its silence timer.
Advances the timer by dt and returns whether it has expired; a dt that is not a finite number expires it until it is fed.
dt
A deadman timer that expires unless fed often enough.