Turtle - Dig 3 x 3 Tunnel

-- This will dig a 3 x 3 tunnel, place torches and
-- return. Place the turtle one block up
-- from the floor.
-- Usage: 3tunnel 5
-- It will mine a 3 x 3 tunnel, 5 blocks long.

-- Original code by SeleckPlays.
-- https://www.youtube.com/watch?v=ftiOe6ztQg4
--  Slightly modded by 25hz

function digIt()
  while turtle.detect() do
    turtle.dig()
    os.sleep(1.0)
  end
  turtle.forward()
  while turtle.detectDown() or turtle.detectUp() do
    turtle.digUp()
    turtle.digDown()
  end
end

function placeTorch()
  turtle.back()
  turtle.turnLeft()
  turtle.forward()
  turtle.select(13)
  turtle.placeUp()
  turtle.back()
  turtle.turnRight()
  turtle.forward()
end

local run = 0
local j = 0
local k = 0

term.write("Tunnel length?  ")
run = read()

-- This places the torches.  Change
-- the number after the % sign to
-- change how far apart the torches are.
for i = 1, run do
  k = i - 1
  j = k % 5

  if j == 1 then
    placeTorch()
  end

  digIt()
  turtle.turnLeft()
  digIt()
  turtle.turnRight()
  turtle.turnRight()
  turtle.forward()
  digIt()
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.forward()
  turtle.turnRight()
end

-- This makes the turtle return to start
-- at ground level.
turtle.down()
turtle.turnRight()
turtle.turnRight()
for i = 1, run do
  turtle.forward()
end