This example demonstrates how to merge data from two CSV files asynchronously using D3 v4. It shows the combined dataset in a `<pre>` element, displaying each person’s name, total, and color description. The code first loads `file1.csv` and builds a D3 `d3.map` keyed by name, then loads `file2.csv` and uses its row function to fetch matching entries from the map and assign the `desc` field. The final callback logs the fully merged array via `JSON.stringify`.