/*Source*/ import Lsystem; size(8cm,0); string[][] rules={{"F","FF"}, {"H","+F+FH++FFH++F+FF+FH++FFH++F+F-"}}; Lsystem H=Lsystem("+H",rules, La=90); H.iterate(5); draw(H.paths(), white); shipout(bbox(3mm, Fill(black)));