What is the other cable on the brake lever?

Just bought a 2nd hand Assassin 800w. I'm stumped as to what the other cable on the brake handle is. Obviously one is the brake cable itself but the black one next to it looks like an electric wire. Both the left and right levers have them.

Should be a brake switch that cuts the power when the brake is pulled.
Most bikes will work with those disconnected but it is a good safety feature.