This example renders a hierarchical dataset of world regions and countries as a tidy tree visualization, with the root at the left and leaves extending rightward. The tree layout positions nodes in a parent-child structure, and horizontal links connect them using `d3.linkHorizontal`. Labels display each region’s name, with font size scaling by depth and text anchors varying for leaf versus internal nodes. The visualization supports pan and zoom via `d3.zoom`, and loads the nested JSON data using `d3.json`.