This example shows a yellow smiley face drawn with SVG shapes whose eyebrows animate upward and then back down. It demonstrates basic DOM manipulation with D3.js. The code uses `d3.select` and `svg.append` to build the face's circle, eye, and rectangular eyebrow elements, while the mouth is drawn with the `d3.arc` path generator. Eyebrow motion is achieved by chaining `transition().duration(2000)` calls on the brows’ parent group, moving it up and then returning it to its original position.