Simple push and pop circuit like in the old diode computer test days where PUSH (the left switch, popular still in ASM) meant push the button to turn on the light bulb. After you screw in another light bulb because its counter part POP (the right switch) meant the light bulb was blown, or popped at the push of the button. Pop later evolves into off. I've even put in some extra light bulbs for playing around with testing.
- nforystek
