This example shows a dual-line chart comparing stock close and open prices over time, with two colored axes (steel blue for close, red for open) to distinguish the scales. It uses D3 v5’s `d3.csv` to load the data, `d3.timeParse` to format dates, and `d3.scaleTime`/`d3.scaleLinear` for the x and y ranges. The lines are drawn with `d3.line` and appended as SVG paths, with axes rendered via `d3.axisBottom`, `d3.axisLeft`, and `d3.axisRight`. Data comes from `data4.csv`.