dom manupulation
This example demonstrates the simplest possible DOM manipulation with D3 version 7, rendering the text “Hello D3 version 7” in the center of a web page. It uses the `select` function from the D3 library to target the `<body>` element and the `.text()` method to set its content. The page loads D3 from a CDN via a script tag, and the code runs from a separate bundled JavaScript file. No data or complex rendering is involved; the focus is purely on showing the basic syntax and setup required to begin using D3.