This example demonstrates two reusable legend components rendered as SVG: a color legend for ordinal scales and a size legend for quantitative scales. The color legend displays fruit categories (apple, lemon, lime, orange) as colored circles, while the size legend uses a square-root scale to map numeric values to circle radii. Both legends are built with D3 v5, using `scaleOrdinal` and `scaleSqrt`, with custom functions that handle enter/merge/exit selections. The code imports `select` from D3 and renders the legends via the `call` method.