This example demonstrates the process of loading and parsing external data in D3.js, using the classic Iris flower dataset. The visualization fetches a CSV file with `fetch`, parses it with `d3.csvParse`, and converts numeric columns from strings to numbers. Once the data arrives, the application logs the parsed dataset to the console and updates its state to trigger a re-render, illustrating a unidirectional data flow pattern with D3 v7 and a simple state management approach.