text: let c1;
  let c2;
  let c3;
  let counter = 0;
  function setup() {
    createCanvas(windowWidth, windowHeight);
    c1 = new Circle(width / 2, height / 2, 100, 75);
    c2 = new Circle(width / 2, height / 2, 150, 100);
    c3 = new Circle(width / 2, height / 2, 175, 125);
  }
  
  function draw() {
    background(220);
    strokeWeight(0);
  
    fill(155, 0, 155);
    if (counter > 200) {
      c3.update();
    }
    c3.draw();
  
    fill(155, 234, 155);
    if (counter > 100) {
      c2.update();
    }
    c2.draw();
  
    fill(0, 155, 155);
    c1.update();
    c1.draw();
  
    counter++;
  }
  
  class Circle {
    constructor(x, y, w, size) {
      this.x = x;
      this.y = y;
      this.w = w;
      this.size = size;
      this.angle = 0.0;
      this.inc = TWO_PI / 850.0;
    }
  
    update() {
      this.size = this.size + 1 * sin(this.angle);
      this.angle = this.angle + this.inc;
    }
  
    draw() {
      ellipse(this.x, this.y, this.w, this.size);
    }
  }
  