This visualization shows a hierarchical tree of hip replacement services, branching from countries to cities, institutions, and experts, with each level sorted by its ranking metric. The code uses D3.js v7 to build and render the tree structure from CSV data fetched via `d3.csv`, applying `d3.hierarchy` and `d3.tree` layouts. It renders as an SVG with an animated collapse-and-expand behavior for nodes, where deeper levels are initially collapsed until clicked. The dark blue background (`#000033`) and horizontal link paths (`d3.linkHorizontal`) create a readable flow across the full window width.