let y = 25;

​

function draw() {

  background(255);

  fill(value);

  rect(25, y, 50, 50);

}

​

function keyPressed() {

​

​

  // if you press up, move up

  if (keyCode === UP_ARROW){

    y = y - 10;

  }

  if (keyCode === LEFT_ARROW) {

    value = 255;

  } else if (keyCode === RIGHT_ARROW) {

    value = 0;

  }

}