This example demonstrates a D3 v4 force-directed graph whose three nodes can be dragged individually, while a Voronoi polygon behind each grouped element expands the clickable and hover area. Hovering activates a node's entire group, highlighting its circle and revealing its hidden text label. The simulation uses `d3.forceSimulation` with charge, link, and center forces, and recomputes the Voronoi overlay on every tick via `d3.voronoi`. The code dynamically adds and removes nodes and links on timed intervals using `d3.interval` and `d3.timeout`, updating the SVG paths, lines, and circles accordingly.