random moving turtle

while true do
r=math.random(1,10)
x=0
while x<=r do
if turtle.detect()==false then
turtle.forward()
sleep(0.2)
else
if turtle.detectDown()==true then
turtle.up()
end
end
x=x+1
end
r=math.random(0,2)
x=0
while x<=r do
turtle.turnRight()
x=x+1
end
if turtle.detectDown()==false then
turtle.down()
end
end