TunnelBridge

arg = {...}
local length = arg[1]
local placeDown = arg[2]
print(length)

function layer()
  turtle.dig()
  turtle.forward()
  for i=1, 3 do
    turtle.turnLeft()
    turtle.dig()
    turtle.turnRight()
    turtle.turnRight()
    turtle.dig()
    turtle.turnLeft()
    turtle.digUp()
    if i<3 then
      turtle.up()
    end
  end
  turtle.down()
  turtle.down()
--[[
    turtle.select(16)
    turtle.digDown()
    turtle.placeDown()
    turtle.turnLeft()
    turtle.forward()
    turtle.turnRight()
    turtle.digDown()
    turtle.placeDown()
    turtle.turnRight()
    turtle.forward()
    turtle.forward()
    turtle.turnLeft()
    turtle.digDown()
    turtle.placeDown()
    turtle.turnLeft()
    turtle.forward()
    turtle.turnRight()
  ]]
end

for i=1, length do
  layer()
  if i<#length then
    turtle.dig()
  end
end