This line chart example presents two datasets: ticket prices by year and Klout scores by day. Clicking color swatches animates the chart between the two data sets, updating both the x- and y-axes, and the line’s gradient stroke. The visualization is built with D3 v4, using SVG rendering and transitions to animate axis rescaling and path redrawing. The code uses `d3.timeParse`, `d3.scaleTime`, `d3.scaleLinear`, `d3.axisBottom`, and `d3.line` for drawing the line.