{
const myWidth = Math.max(640, width);
const ctx = DOM.context2d(myWidth, 100);
ctx.strokeStyle = '#959';
while (true) {
ctx.clearRect(0, 0, myWidth, 100);
ctx.beginPath();
for (let i = 0; i < myWidth; i += 2) {
ctx[i ? 'lineTo' : 'moveTo'](i, 50 +
Math.cos((Date.now() / 2000) - i / 5) *
Math.cos((Date.now() / 2000) - i / 20) * 20);
}
ctx.stroke();
yield ctx.canvas;
}
}