Fork of D3 Starter
A yellow smiley face rendered in SVG uses D3 v7 selections to build concentric circles for the head, eyes, and pupils, plus an arc-generated mouth. A continuous while loop chains `transition()` calls on the pupil elements, animating their `cx` and `cy` attributes to shift diagonally, then downward, and back to center. The code imports `select` and `arc` from the D3 module, with the mouth path’s shape defined by inner and outer radii and angular start and end values.