This example visualizes a small graph of seven nodes and eight links using WebCola’s constraint-based layout, with nodes grouped into translucent, colored rectangles. The graph data comes from `graph.json`, and the visualization renders as SVG via D3 v4, where nodes are draggable and zoomable. WebCola’s `d3adaptor` handles the layout, enforcing link distances and avoiding overlaps, while D3’s `tick` handler updates node, link, and group positions. Double-clicking a node releases it from its fixed position, letting the layout re-optimize around the user’s manual placement.