Mineshaft digger

local function drop()
   for i=1,15 do
      turtle.select(i)
      turtle.dropDown()
   end
   turtle.select(1)
end

local function placeChest()
   turtle.turnLeft()
   turtle.dig()
   turtle.forward()
   turtle.select(16)
   turtle.placeDown()
end

local function goingDown()
   for i=1,5 do
      turtle.digDown()
      turtle.dig()
      turtle.forward()
   end
   for i=1,4 do
      turtle.back()
   end
   turtle.down()
end

local function goingUp()
   turtle.dig()
   turtle.forward()
   for i=1,4 do
      turtle.digUp()
      turtle.up()
   end
   for i=1,4 do
      turtle.down()
   end
end

local function goingDownFinal()
   turtle.digDown()
   turtle.down()
   turtle.dig()
   turtle.forward()
   turtle.digDown()
   turtle.down()
   for i=1,3 do
      turtle.dig()
      turtle.forward()
      turtle.digUp()
      turtle.digDown()
   end
   turtle.down()
   turtle.back()
   turtle.digDown()
   turtle.down()
   turtle.dig()
   turtle.forward()
   turtle.digDown()
   turtle.down()
   turtle.turnRight()
   turtle.dig()
   turtle.forward()
   for i=1,4 do
      turtle.digUp()
      turtle.up()
   end
   for i=1,4 do
      turtle.down()
   end
end
--------
--Main--
--------

for i=1,50 do
   goingDown()
end
goingDownFinal()
for i=1,54 do
   goingUp()
end
placeChest()
drop()
turtle.back()
turtle.turnRight()
turtle.forward()
print("Done!")