What Is That!?!

I was looking in my repair manual for 85-88 Safari's, and I saw this picture of the interior. Right next to the Cig. Lighter theres a switch that can move up and down. I dont have one on my van and its just one of those things that you have to find out what it is. Can someone tell what that switch does?

it turns the interior lights on or off when one of the doors are open .