Fence placement

args={...}

if (args[2]~=nil) then
  l=args[2]
else
  l=64
end

function needsFuel()
  local level=turtle.getFuelLevel()
  print("-----------")
  print("Fuel Level:")
  print(level)
  print("-----------")
  if level=="unlimited" or level>500 then
    return false
  else
    turtle.select(16)
    turtle.refuel()
  end
end

function checkslot()
  local i=1
  while true do
    if turtle.getItemCount(i)==0 then
      i = i+1
      if (i>8) then
        print("No items available.")
        return false
      end
    else
      return i
    end
  end
end

function moveForward()
  needsFuel()
  while not turtle.forward() do
    turtle.dig()
  end
end

function moveDown()
  needsFuel()
  while not turtle.down() do
    turtle.digDown()
  end
end

function moveUp()
  needsFuel()
  while not turtle.up() do
    turtle.digUp()
  end
end

function place()
  slot = checkslot()
  if checkslot==false then
    return false
  else
    turtle.select(slot)
  end
  while not turtle.placeDown() do
    turtle.digDown()
  end
end

function makeline(e)
  for i=1,e do
    moveForward()
    place()
  end
end

function pickupFences(e)
  for i=1,e do
    moveForward()
  end
end

function buildMine()
  makeline(l)
  turtle.turnLeft()
  makeline(l)
  turtle.turnLeft()
  makeline(l)
  turtle.turnLeft()
  makeline(l-1)
  turtle.forward()
  turtle.turnLeft()
  turtle.forward()
end

function collectFences()
  moveDown()
  pickupFences(l-1)
  turtle.turnLeft()
  pickupFences(l)
  turtle.turnLeft()
  pickupFences(l)
  turtle.turnLeft()
  pickupFences(l-1)
  moveUp()
end

if (args[1]=="new") then
  buildMine()
else
  collectFences()
  buildMine()
end