A bubble chart displays the Flare class hierarchy, encoding each class’s count as the area of a circle. Circles are packed tightly with d3.pack, colored by package using d3.scaleOrdinal and d3.schemeCategory20c, and labeled with clipped text. The code loads CSV data via d3.csv, builds a hierarchy with d3.hierarchy, and renders SVG circles, clipPaths, and titles. It follows an implementation by Jeff Heer and is forked from mbostock’s block.