/** * Inheritance *  * A class can be defined using another class as a foundation. In object-oriented * programming terminology, one class can inherit fi elds and methods from another.  * An object that inherits from another is called a subclass, and the object it  * inherits from is called a superclass. A subclass extends the superclass. */SpinSpots spots;SpinArm arm;void setup() {  size(200, 200);  smooth();  arm = new SpinArm(width/2, height/2, 0.01);  spots = new SpinSpots(width/2, height/2, -0.02, 33.0);}void draw() {  background(204);  arm.update();  arm.display();  spots.update();  spots.display();}class Spin {  float x, y, speed;  float angle = 0.0;  Spin(float xpos, float ypos, float s) {    x = xpos;    y = ypos;    speed = s;  }  void update() {    angle += speed;  }}class SpinArm extends Spin {  SpinArm(float x, float y, float s) {    super(x, y, s);  }  void display() {    strokeWeight(1);    stroke(0);    pushMatrix();    translate(x, y);    angle += speed;    rotate(angle);    line(0, 0, 66, 0);    popMatrix();  }}class SpinSpots extends Spin {  float dim;  SpinSpots(float x, float y, float s, float d) {    super(x, y, s);    dim = d;  }  void display() {    noStroke();    pushMatrix();    translate(x, y);    angle += speed;    rotate(angle);    ellipse(-dim/2, 0, dim, dim);    ellipse(dim/2, 0, dim, dim);    popMatrix();  }}