This example demonstrates two custom legend components—one for a categorical color scale and one for a quantitative size scale—rendered as SVG within a D3 v5 visualization. The color legend uses `scaleOrdinal` to map fruit names to colors, while the size legend uses `scaleSqrt` to map numeric values to circle radii. Both legends are implemented as reusable functions that receive their parameters via `Object.assign`, following the "Towards Reusable Charts" pattern. The code explicitly sets properties on the component functions before invoking them with `.call()`, and each legend updates its groups, circles, and text elements through D3's select, enter, merge, and exit operations.