This example shows violin plots of sepal length distributions for three iris species, using a kernel density estimate to depict the shape of each group's data. The code loads the Iris dataset via `d3.csv`, then applies `d3.nest()` to group by species and computes densities with a custom `kernelDensityEstimator` using the Epanechnikov kernel. It renders the resulting smoothed areas as SVG paths with `d3.area()` and `d3.curveCatmullRom`, positioned using `d3.scaleBand` and `d3.scaleLinear` scales.