This example shows the age distribution of a population as a donut chart, with each slice labeled by its age bracket and colored using an ordinal scale. The visualization is rendered as SVG using D3 v4, applying `d3.pie` to compute the arc angles and `d3.arc` to generate the paths and label positions. Data is loaded from a local CSV file with population counts per age group, and the chart centers itself in an 960×500 viewport. The code uses D3’s data join to append arc groups, paths, and text elements.