Suppose that you are writing an application to control a cooling fan speed over Bluetooth. The fan has four pre-defined speeds. Fill out the Fan class that stores the speed of a cooling fan, and enables the application to increase, decrease and retrieve the current speed of the fan over Bluetooth public class Fan { static final int OFF = 0; static final int LOW = 1; static final int MEDIUM = 2; static final int HIGH = 3; // declare instance variables // initializes fan speed to OFF public Fan () { // implement this method } // increase fan speed one level up public void increaseSpeed () { // implement this method } // decrease fan speed one level down public void decreaseSpeed () { // implement this method } // returns the current fan speed public int getSpeed () { // implement this method } }