Which key function is associated with the AAN LT switch in the cockpit?

The AAN LT switch in the A320 cockpit is specifically associated with testing all annunciator lights. When the AAN LT switch is activated, it serves to illuminate all the warning, caution, and advisory lights on the overhead panel. This functionality is crucial during pre-flight checks, as it allows pilots to ensure that all lights are operational and functioning correctly. Testing the annunciator lights helps confirm that any alerts that may need to be displayed during flight will be visible to the crew in the event of an emergent situation. This contributes to overall safety and readiness for various flight operations.