This fork of a simple line chart visualizes the Keeling Curve, plotting atmospheric CO2 concentration over time using d3.scaleTime and d3.scaleLinear. The viz.js file constructs the line with d3.line, applies axes via axisLeft, and renders axis labels from the @curran/axis-labels library. Data comes from the @curran/keeling-curve-data package, while the code also references remote CSV and JSON URLs for potential alternate datasets. The chart includes a styled inner rectangle and semi-transparent circular markers, with configuration options passed from index.js.