This example shows an interactive tree diagram with expandable and collapsible nodes. The visualization displays hierarchical data, including named nodes like "Swarna Kumari" and "Lakshmi," with clickable circles that toggle child visibility. Built with React and D3.js v3, it uses `d3.layout.tree` to compute positions and `d3.svg.diagonal` for curved links. SVG elements render nodes and text, while transitions animate node and link movement over 750 milliseconds when collapsing or expanding branches.