This example displays a pie chart showing the distribution of bedroom counts in a housing dataset. The visualization aggregates the data using d3.rollup, then renders the chart with d3.pie and d3.arc, with slices colored by d3.scaleOrdinal and d3.schemeCategory10. Interactive tooltips appear on mouseover, and labels are positioned using path.centroid. A legend encodes the bedroom categories. The data is loaded via d3.csv from a GitHub gist, and the chart is rendered as an SVG with a tooltip div styled in CSS.