Based on how the book describes a heat pump in sec 16.3 how does a heat pump prove law of conservation of energy

The law of conservation of energy states that: "energy cannot be created nor destroyed. It can only be transformed from one form to the other". A heat pump transfers heat from a colder area to a warmer area. As the conservation of energy goes, the energy that comes in, must equal the energy that comes out. Although no machine is 100% efficient, the missing energy is supplied by an external energy source, such as electricity.