Let's make a face with D3.js!
A smiley face rendered in SVG animates its eyebrows in a looping motion. The example demonstrates fundamental D3.js DOM manipulation by appending circles, rectangles, and a path to an SVG group, using `d3.arc` for the mouth. The eyebrows move via chained `transition().duration()` calls that shift their vertical position. The code uses `d3.select` and `d3.arc` from d3.v5, with all shapes positioned through SVG attributes and a centered group transform.