This example demonstrates a collapsible tree diagram where each click on a node generates a fresh tree layout. It uses d3.hierarchy and d3.tree to compute the node positions, with d3.transition to animate the expanding and collapsing of branches. The visualization updates the SVG elements dynamically, reassigning parent-child relationships and rebuilding the tree structure on each interaction. Data is derived from a hardcoded hierarchical JSON object, rendered as colored circles and connecting links.