Fork of Smiley Face Part III
A smiley face is rendered as a static SVG graphic, with a yellow circular head, black outline, two dark eyes, and a curved mouth. The example demonstrates a React component that uses D3’s `arc` generator to define the mouth path, while other shapes are drawn with SVG elements. The component places all parts inside a `<g>` transform for centering, using D3 v5 and React 16.9.