It would light itself every night. You would put a sensor/solar panel out a window with natural light on the first night. The first two LED's would light. When the light came on, it would shut down. When the light was no more three LED's would light. And so on. On the eighth night, you'd take it down, hit the reset button, and lo, it would be ready for the next year.

I'm going to make one, with an Arduino, for my landlord. Just cause I can.