This pie chart visualizes the distribution of diabetes cases across five age ranges (0-20, 21-40, 41-60, 61-80, and 81+). The code fetches a CSV file from a GitHub repository, parses it with `d3.csvParse`, and counts occurrences per age group. It renders the chart using D3.v7's `d3.pie` layout and `d3.arc` generator within an SVG, with a categorical color scale (`d3.scaleOrdinal` with `d3.schemeCategory10`). A legend and labels for each segment are added dynamically via D3 selection and append methods.