This visualization, titled “bars of bars,” displays four years of numeric values as grouped bar charts. Each year’s value is rendered as a vertical stack of small rectangles, with positive values extending upward from a zero line and negative values extending downward. The code uses d3.v4 to parse dates, apply linear and band scales, and draw axes. Rectangles are generated via d3.range and appended inside SVG groups, with steelblue fills, based on the data from the gist.