This area chart visualizes average life expectancy by year, using temperature data from San Francisco as the underlying dataset. It renders an SVG with D3 v5's `scaleTime`, `scaleLinear`, `area`, and `curveBasis` to draw the filled path, while axes are generated with `axisBottom` and `axisLeft`. The data is loaded via `csv` from a GitHub gist, and the chart includes custom styles for the title and axis labels.