Getting function not found errors when uploading code

Backlight management is quite a nifty thing depending on the requirements. I assume, you require:

1. light goes on on button down.
   
2. the timeout for light to go off starts on button up.
   
3. existing timout is cleared on button down.
   
   

In other words, light is on when button is down and stays on for another 2 seconds after button has gone up.