QUESTION $6.$ Explain this sample class code line by line $($or in code blocks$)$: $(10$ MARKS$)$public class Circle $\{$ private double radius; public Circle$($double r$)\{$ radius $=$ r; $\}$ public double getRadius$()\{$ return radius; $\}$ public double area$()\{$ return Math.PI $*$ radius $*$ radius; $\}$ public double circumference$()\{$ return $2*$ Math.PI $*$ radius; $\}\}$public class Main $\{$ public static void main$($String$[]$ args$)\{$ Circle circle $=$ new Circle$(5)$; System.out.println$("$Radius: $"+$ circle.getRadius$())$; System.out.println$("$Area: $"+$ circle.area$())$; System.out.println$("$Circumference: $"+$ circle.circumference$())$; $\}\}$