{
const height = 20;
const context = DOM.context2d(width, height);
while (true) {
const x = ((Math.sin(Date.now() / 1000) + 1) / 2) * (width - height);
context.clearRect(0, 0, width, height);
context.fillRect(x, 0, height, height);
yield context.canvas;
}
}