Closed filled polygon in data space. See Bland.polygon/4.
Unlike Area, which sweeps a curve back to a baseline, Polygon
fills whatever arbitrary shape its vertices describe. The last
point is implicitly connected back to the first.
Fields:
:xs,:ys— vertex coordinates (same length):hatch— optional fill pattern. Whennil, the polygon is stroke-only.:stroke— outline dash preset (default:solid):stroke_width,:label