This example visualizes the Iris dataset as a scatter plot, mapping sepal length on the x-axis and petal length on the y-axis. Data points are drawn as different shapes corresponding to the three iris species, with a custom shape legend explaining the mapping. The code uses d3.csvParse to load the data and d3.scaleLinear, d3.scaleOrdinal, and d3.symbol to encode values and shapes. Axes are generated with d3.axisLeft and d3.axisBottom, while the visualization updates dynamically as data loads via a simple state-based rendering pattern.