--Pastebin name: tUFHwJn3
--Position this device in the branch tunnel

local tArgs = { ... } -- obtain tunnel length and turn around options
if #tArgs ~= 2 then
    print( "Usage: tunnel <length>, and then turn around: <y> or <n>" )
    return
    end

local length = tonumber( tArgs[1] ) -- Check if the tunnel length is > 1
if length < 1 then
    print( "Tunnel length must be positive" )
    return
    end

local turn = ( tArgs[2] ) -- Check if the turtle turn around option is y or n
if not( turn ~= ( "y" ) or turn ~= ( "n" )) then
    print( "Indicate whether to have the turtle go down to the next course and turn around" )
    return
    end

local fuel = turtle.getFuelLevel()
if fuel < 80 then
    print("you must add more fuel")
    return
    end

--definition of functions follows

local function tryDig() -- This function digs forward one block
    while turtle.detect() do
        if turtle.dig() then
            sleep(0.5)
        else
            return false
        end
    end
    return true
    end

local function tryDigUp() -- This function digs up one block
    while turtle.detectUp() do
        if turtle.digUp() then
            sleep(0.5)
        else
            return false
        end
    end
    return true
end

local function tryDigDown() -- This function digs down one block
    while turtle.detectDown() do
        if turtle.digUp() then
            sleep(0.5)
        else
            return false
        end
    end
    return true
end