D3-1: Making a face
A smiling face is drawn using SVG shapes, with a yellow circle for the head, black circles for eyes, and a mouth created as an arc path. The example demonstrates basic SVG element creation and positioning through D3’s `select`, `append`, and `attr` methods, along with the `arc` generator to define the mouth’s shape. Coordinates are centered by translating a group element, and dimensions are read from the SVG attributes. The code uses D3 v5 and renders entirely in SVG.