You are in a room with 3 light switches. These switches are connected to 3 separate light bulbs in an ajoining room. Access to the ajoining room is via a door that remains closed, there are no windows, other people etc etc. You are allowed to enter the ajoining room once and then return. At no time can you view the light bulbs whilst being able to manipulate the light switches. Under these conditions, how do you identify which switch is connected to which light bulb?