import turtle

SIZE = 5
ANGLE = 108
X0 = 0 
Y0 = 400
DOUBLES = 14 # 14 takes "many minutes" on my machine. Each extra double doubles space and time required.
thue = "ABBA"
turtle.penup()
turtle.speed(0)
turtle.setx(X0)
turtle.sety(Y0)

def extend(thue):
	opp = ""
	for i in thue:
		if i == "A":
			opp += "B"
		else:
			opp += "A"
	return thue + opp

for i in range(14):
	thue = extend(thue)
	
turtle.pendown()
for t in thue:
	if t == "A":
		turtle.forward(SIZE)
	else:
		turtle.forward(SIZE*2)
	turtle.right(ANGLE)