This example builds a smiling face from basic SVG shapes: a yellow circle for the head, two circles for eyes, rectangles for eyebrows, and a semi-circular mouth drawn with `d3.arc`. The eyebrows animate upward and back down using chained `transition().duration()` calls on a `<g>` element. The code uses D3 v5 selection methods and `d3.arc`, with the face centered via a translation transform. The animation runs once on load, and no data source is involved.