This example visualizes the total number of Olympic medals won by each country for each Winter Games year, broken down by gold, silver, and bronze counts. A stacked bar chart displays the medal distribution across countries and years, with each bar segment representing a medal type. The code loads a CSV dataset from the Winter Olympic Medals 1924–2018 Kaggle dataset, converts numeric fields, and uses `d3.rollup` to group and sum medal counts by year and country. The flattened data structure is then prepared for rendering, though the main function currently outputs a sample data object as JSON text rather than drawing the chart.