This example displays a hierarchical family tree as a node-link diagram rendered in SVG using D3.js v5. The visualization uses `d3.hierarchy` and `d3.tree` to compute the layout from nested JavaScript data objects. Each node is represented by a circle whose radius corresponds to a numeric `value` property, while link strokes and circle fills derive color from the `level` field, and circle borders use the `type` field. Text labels show each person’s name, positioned to the left for internal nodes and right for leaves. The code manually constructs curved link paths with `d` string templates rather than using a curve generator.