This code runs on a ATTiny 84 using hall effect senors as the "switches" 

The device if not lit will go to sleep after ten minuets of inactivity. 
It will then wake up every two seconds, power up the sensors and look
to see the "power putton" is being pushed by holding  magnet near the power sensor.
If that is not happening it will then go back to sleep and start over again.
This sleep mode is very low power. 
In my case around 7 microamps.

If the button is being "pressed" then the hardware resets all inputs and outputs and then turn on the light.

The light uses the NV ram in the ATTniny 84 to remember the power level last used and will always turn on at 
the last used intensity level.