A Color class has three public, integer-returning accessor methods: getRed, getGreen, and getBlue, and three protected, void-returning mutator methods: setRed, setGreen, setBlue, each of which accepts an integer parameter and assigns it to the corresponding color component. 
The class, AlphaChannelColor-- a subclass of Color-- has an integer instance variable, alpha, containing the alpha channel value, representing the degree of transparency of the color. AlphaChannelColor also has a method named dissolve (void-returning, and no parameters), that causes the color to fade a bit. It does this by incrementing (by 1) all three color components (using the above accessor and mutator methods) as well as the alpha component value. 
prepare the dissolve method.