This example shows an interactive radial dendrogram of country population data, rendered as SVG. The visualization uses `d3.cluster` to compute a circular tree layout, with leaf nodes labeled by country name and sized by text depth. Pan and zoom are implemented via `d3.zoom` on a background rectangle, transforming the containing `<g>` element. The code loads hierarchical data from `countryHierarchy.json` and projects node positions using trigonometric functions to map tree coordinates to a radial polar layout.