var speed;

​

function setup() {

  noStroke();

  createCanvas(400, 400);

  print("hello world");

  print(10);

  cat = 5;

  speed = 2;

}

​

function draw() {

  background(220);

  fill (255,cat,0);

  ellipse(cat,100,40,40);

  ellipse(width/2,height/2,20,20);

  cat = cat + speed;

  if(cat > width){

    speed = speed * -1;

  }

  if(cat < 0) {

    speed = speed * -1;

  }

}