This example demonstrates a basic heatmap-building workflow using D3.js v5. It loads a CSV file via `d3.csv` and preprocesses the data by parsing string values into floating-point numbers with a custom callback function. The code logs the sum of the x and y coordinates for each row to the console, showing how raw data is read and transformed. A large "Hello VizHub!" message is displayed on screen, styled with an Ubuntu font and a dark blue background. The project relies on ES6 modules and external stylesheets for its structure and presentation.