This example displays an animated, collapsible tree diagram representing a three-level family hierarchy, with nodes showing names and links connecting parents to children. Clicking a node toggles the visibility of its subtree, smoothly transitioning the layout as branches expand and collapse. Built with D3.js version 3.5.17, the visualization uses the `d3.layout.tree` and `d3.svg.diagonal` APIs to compute the node positions and draw curved link paths, while SVG transitions animate the changes over 750 milliseconds. The data is hardcoded as a nested JavaScript array in the HTML file.