This example draws a sad emoji face using SVG primitives in D3 v7. A yellow circle forms the face, while circles, rectangles, and an arc path construct the eyes, eyebrows, and mouth. The eyebrows repeatedly animate upward and downward via chained `transition().duration(2000)` calls, creating an expressive, looping motion. The code imports `select` and `arc` from the D3 module and loads the library via UNPKG.