This example displays a time-series line chart of sentiment values loaded from a CSV file, with a mouseover interaction that reveals the exact sentiment value at the nearest data point. A transparent overlay rectangle captures mouse events, and a bisector function finds the closest time value to the cursor position. The chart uses D3 v3 with SVG rendering, including axes, a steelblue line path, and a focus circle with text label that updates dynamically on mousemove. The code relies on d3.csv, d3.svg.line, d3.svg.axis, and d3.bisector.