This example loads the classic Iris flower dataset from a CSV file and computes the average sepal length for each of the three species using D3’s `flatRollup` and `sum` functions. The results are displayed as a formatted JSON summary inside a `pre` element in the browser. Built with D3 v7, the visualization demonstrates asynchronous data fetching with `fetch` and `csvParse`, as well as the use of local ES6 modules for organizing the code.