256x256x1 Hole

for h=1,256 do
    for i=1,512 do
        turtle.refuel(1)
        turtle.dig()
        turtle.forward()
    end
    turtle.turnLeft()
    turtle.dig()
    turtle.forward()
    turtle.turnLeft()
    for i=1,512 do
        turtle.dig()
        turtle.forward()
    end
    turtle.turnRight()
    turtle.dig()
    turtle.forward()
    turtle.turnRight()
end