Adding a switch to an electric cord

I have a few lights in the house which do not have switches on them. There’s a vintage marquee light in the shop right now which I have to bend over and plug in when I want to turn it on. So I finally got fed up and decided to remedy this stupid situation and headed to my local hardware shop where the guy shoved one of these switches in my hand and assured me that it was a piece of cake.

And it was!

Check it out:

Adding a switch to an electric cord