This example shows a hierarchical graph visualization of event trace data, using grouped rectangles to represent nested records and colored nodes to distinguish between entities, attributes, and relations. The visualization is rendered using D3 v4 and the WebCola layout library (accessed through `cola.d3adaptor`) to position and group elements with constraints-based optimization. A zoomable SVG canvas displays the graph, with a color scheme defined in a separate JSON file. The graph data comes from `graph.json`, which specifies group structures and leaf descriptions.