This fork of a D3.js v3 collapsible tree renders hierarchical JSON data using rectangular nodes colored by type. Clicking a node expands or collapses its children with a smooth animation, while links display directions and tooltips appear on hover. The visualization supports zooming and dragging via `d3.behavior.zoom`. Node layout and depth are computed with `d3.layout.tree`, and the SVG output dynamically resizes based on tree breadth and depth, with custom styling defined in CSS classes.