Attract / Doorknob

In the faint light, because it is not clear keyhole look at the location, often stuck at the gate. Suppose there is a keyhole around the magnetic case, the keys will be attracted to the keyhole, so to solve the problem of less than a keyhole. For the blind case, you can also rely on smooth magnetic attracted to open the door to find the key to a smooth hole.
The concept is to imitate the process of a black hole that engulfs the material transferred to the keyhole to attract the key to this matter, to the weak external magnetic to the keyhole of the strong magnetic feature to open the door.