This example visualizes population over time by region from 1950 to 2100, using data from the UN Population Estimates. It displays multiple line paths, each colored by region, with an ordinal color scale and a custom legend. The visualization uses d3.csv, d3.nest, d3.scaleTime, d3.scaleLinear, d3.line with curveBasis, and d3.axisBottom/axisLeft. Data is melted from wide to long format, filtered for regions, and rendered as SVG paths with mix-blend-mode multiplication.