This example shows a hierarchical data visualization of hip replacement experts, organized as a tree with root "Hip Replacement" branching into countries, cities, institutions, and expert names. The data is loaded asynchronously from a CSV file using D3's `d3.csv` function. The visualization updates in response to the dataset, with the tree layout computed using `d3.tree()` and node positions linked via `d3.linkHorizontal()`. SVG rendering and animation are implemented with D3 v7, with a dark blue background applied to the page.