Smiley face
This example renders a simple smiley face using React and D3’s `arc` generator to create the mouth, with circles for the eyes and face. The face is drawn as a yellow circle with a black stroke, positioned at the center of an SVG canvas. The code uses D3’s `arc()` API to compute the mouth path, while React manages the SVG elements declaratively. The rendering is static, with no interactivity, and relies on fixed coordinates for the eyes, mouth radius, and stroke width.