Branch

Args = {...}

function digfor()
  while turtle.detect() do
    turtle.dig()
    os.sleep(0.5)
  end
  turtle.forward()
end

function digup()
  while turtle.detectUp() do
    turtle.digUp()
    os.sleep(0.5)
  end
end

function torch()
  turtle.turnRight()
  turtle.turnRight()
  turtle.select(2)
  turtle.place()
  turtle.turnRight()
  turtle.turnRight()
end

function checkdown()
  if turtle.detectDown() == false then
    turtle.select(3)
    turtle.placeDown()
  end
end

function checkfuel()
  fuel = turtle.getFuelLevel()
  if fuel <= 20 then
    turtle.select(1)
    turtle.refuel(1)
  end
end

if #Args ~= 1 then
  print("Usage: branch <num>")
  n = 0
else
  print("Branching "..Args[1].." blocks forward.")
  print("Fuel: slot 1, torch: slot 2, cobble: slot 3.")
  turtle.select(1)
  for i=1,Args[1] do
    checkfuel()
    n = n + 1
    digfor()
    digup()
    checkdown()
    if n == 7 then
      torch()
      n = 0
    end
  end
  turtle.up()
  for i=1,Args[1] do
    checkfuel()
    turtle.back()
  end
end