No, wait… I meant first class lever. Definition?
There are three basic components of a lever: a fulcrum, the effort and the resistance. The effort would be the door, fulcrum a hook above the door, and the resistance the decoration(a ghoul with the face made from HM, if you were wondering). There is a string with the first end tied to the door and the middle hung on the fulcrum, and the other end on the resistance. The door is pulled, the string is also pulled by the door and the chain reaction starts. The door is and pulled so is the string. Since the string is hung on a hook (F) above the door it lifts up the decor (R) and it give the illusion of a ghoul floating in front of you at the doorstep on your way to your “safe” house. And Voila!