open Level_2; (* (0,0), ..., (21,21) *) build2D(21,21); ringXZ 10 1 YELLOW (10,10); put2D_1x1_BLUE(10,10); put2D_1x1_BLUE(20,10); put2D_1x1_BLUE(0,10); put2D_1x1_BLUE(10,0); put2D_1x1_BLUE(10,20); show2D "Ring";