This example displays the distribution of iris species as a pie chart, with each slice labeled and accompanied by a color-coded legend. It loads CSV data from a GitHub gist, parses numeric fields, and groups records by species using `d3.nest()` and `d3.rollup()`. The chart is rendered with SVG using `d3.pie()` and `d3.arc()`, while `d3.scaleOrdinal` with `schemeCategory10` assigns slice colors and legend swatches.