deepMine

function mineForward()
    while turtle.dig() do end
    turtle.digDown()
    turtle.digUp()
    while not turtle.forward() do end
end

function mineLayer()
    for backAndForth=1,4 do

        for there=1,7 do
        mineForward()
        end

        turtle.turnRight()
        mineForward()
        turtle.turnRight()

        for back=1,7 do
        mineForward()
        end

        turtle.turnLeft()
        mineForward()
        turtle.turnLeft()
    end
end

function layerSetup()
    turtle.turnLeft()
    turtle.forward()
    for downwards=1,3 do
        turtle.down()
        turtle.digDown()
    end
end

function comeHome()
    turtle.turnLeft()
    turtle.forward()
    for upwards=1,12 do turtle.up() end
    turtle.back()
end

if turtle.getFuelLevel() < 300 then --test for enough fuel
    print("Not enough Fuel!")
else
    for depth=1,4 do
        mineLayer()
        layerSetup()
    end
    comeHome()
end