let startLevel = 5;
let step = 20;
up
goto (-3*step*startLevel) (3*step*startLevel)
down
pen thickness:thin
let L=0;
let R=1;
let U=2;
let D=3;
let mv = (dir.
if (dir == L) then (
pen color:darkblue
left 90
fw step
right 90
)
if (dir == R) then (
pen color:blue
right 90
fw step
left 90
)
if (dir == D) then (
pen color:yellow
right 180
fw step