This example shows a hierarchical tree of programming languages, organized by paradigms and domains, with leaf nodes for individual languages. Node shapes encode type—diamonds for the root, squares for internal nodes, and circles for leaves—while color represents the depth, or generation, of each node. The visualization uses the D3 version 7 library, specifically the `d3.hierarchy`, `d3.tree`, and `d3.linkHorizontal` APIs to compute and draw the layout. Hovering over a node reveals a tooltip showing the node’s name and depth, and a legend clarifies the shape and color encoding.