This example visualizes the Iris dataset as a scatter plot with distinct shapes for species, mapping sepal length to the x-axis and petal length to the y-axis. It uses d3.scaleLinear for both axes and d3.scaleOrdinal with symbolsFill to assign shape marks to each species, while a custom shape legend displays the mapping. The visualization loads data via fetch from a GitHub repository, parses it with d3.csvParse, and renders axes using d3.axisLeft and d3.axisBottom. ES6 modules demonstrate code organization across files.