Let's make a face
This example builds a smiling face from basic SVG shapes using D3.js v6. A yellow circle forms the head, with two eyes and a mouth drawn as a path using the `arc` generator. The eyebrows, rendered as rectangles, animate upward and back down via chained `transition().duration(500)` calls. The code imports `select` and `arc` from D3, positions elements relative to a centered group, and uses SVG attributes like `cx`, `cy`, and `d` for layout.