This line chart displays a week of temperature readings from multiple cities, with each city represented by a colored, smoothed line. The visualization uses D3 v5's `nest()` to group data by city and `scaleTime`/`scaleLinear` for axes. A custom `colorLegend` component renders the categorical color scale, while `axisBottom` and `axisLeft` include gridlines. Data comes from a CSV file loaded via `csv()`, and the SVG rendering applies a multiply blend mode to overlapping lines.