This example visualizes the classic Iris dataset, plotting sepal length against petal length for three flower species—setosa, versicolor, and virginica—as colored circles in a D3 scatterplot. Each species has its own linear regression line, computed from the data and drawn as a path, with the lines in blue, red, and green to match the points. The visualization uses D3’s `d3.svg.axis` for axes, `d3.scale.linear` for positioning, and `d3.svg.line` to generate the regression curves, all rendered as SVG elements. The data is embedded directly in the script via a `create_data()` function, and the axes are labeled with the raw measurement units from the dataset.