let circleXPosition = 50;

let redCircleX = 150;

​

function setup() {

  createCanvas(200, 400);

}

​

function draw() {

  background('black');

​

  fill(156, 34, 34);

  circle(circleXPosition, 200, circleDiameter);

  circleXPosition = circleXPosition + 0.2;

  fill(34, 89, 156);

  circle(redCircleX, 200, circleDiameter);

  redCircleX = redCircleX - 0.2;

}