/* Source */
import Lsystem;
size(8cm,0);
string[][] rules={
{"A", "X+X+X+X+X+X+"},
{"X", "[F+F+F+F[---X-Y]+++++F++++++++F-F-F-F]"},
{"Y", "[F+F+F+F[---Y]+++++F++++++++F-F-F-F]"}
};
Lsystem spiral=Lsystem("AAAA",rules,La=15);
spiral.iterate(6);
draw(spiral.paths(), 0.9*green);
shipout(bbox(2mm, Fill(black)));