The Raspberry Pi Simple Electronics extension is an extension released in Scratch 3.0. It allows Scratch to control lights connected to a Raspberry Pi. It is only included with the Raspberry Pi release of Scratch and is not included with any other versions.
when button (0 v) is [pressed v] :: extension hat
<button (0 v) is [pressed v]? :: extension>
turn LED (0 v) [on v] :: extension
toggle LED (0 v) :: extension