This example renders a simple smiley face using React and D3. It draws a yellow circle for the face, two black circles for eyes, and a curved arc for the mouth, all positioned within an SVG canvas. The code uses React’s `ReactDom.render` to mount the app and D3’s `arc` generator to create the mouth path with specified inner and outer radii and angle ranges. SVG circle elements are used for the face and eyes, with stroke styling applied through attributes.