Compact T Flip Flop
This is a fairly standard T flip flop schematic. A T flip flp takes a redstone pulse (like from a button) and turns it into a steady on/off state like a lever.
You would do this because levers are very obtrusive in single-file areas, and you can hide a button or a pressure plate much easier. Very useful for traps or aesthetic areas with redstone contraptions.
So, ready to paste it?
Load up Minecraft and go to your desired area. You need a 4(w)x5(l)x5(h) area. Unfortunately, the bottom layer is just a stone block and air, so it WILL replace anything within the dimensions stated with air.