This example shows a pie chart of the top 10 most frequent math scores from a CSV dataset, with a legend displaying each score and its count. It uses D3.js v7 to load the data via `d3.csv`, aggregate counts, and sort them in descending order. The `d3.pie` and `d3.arc` functions generate the slices, while a custom color palette from `d3.schemeCategory10` colors each slice, and a separate SVG legend is built manually with `rect` and `text` elements.