None. The light bulb contains the seeds of its own revolution.
or
Hey, bud!
or
Five. Four to decide which way the bulb ought to turn, and . . .
or
Because an undocumented worker has been living on his head for the past 2 decades!
or
Fifty — one to screw in the bulb and 49 to guard him/her.
or
Stairs.
or
A garbage truck.
or