How to fill Pattern field
fDraws a line.
cDraws a filled circle.
tTurn left or right, at random.
?Turn left or right or not at all, at random.
nStep forward with no drawing.
-Step backward with no drawing.
dDuplicate - create a child in my direction.
bBranch - 50% chance of creating a child
mMirror - 50% chance direction inverted.