A PathContext that accumulates an SVG path d string. Used for publication vector export: re-run a d3 generator (geoPath, d3-shape, …) into this context and read toPath(). Curves map to native C/Q commands; arcs are flattened to line segments (correct geometry; geo export is polygons/lines, so this is rare).
Assemble styled paths into a standalone SVG document string. Paths with an empty d are skipped. fill defaults to “none” when only a stroke is given, otherwise to the provided fill.