This visualization displays hourly energy demand and generation data for Spain across four years, with a table rendering the raw CSV content for inspection. The code fetches the dataset, parses it using `d3.csvParse`, and stores the parsed rows in application state. Each update triggers a re-render through the `viz` function, which uses D3’s `select` and `join` methods to display the data as JSON-formatted text within a `<pre>` element, driven by a simple state management loop.