turtle Digging stairs ComputerCraft

-- Requires:
-- mining turtle
-- Slot 1, Coal
-- Slot 2, Stairs if you want him to place Stairs

function digMyStairs()
local action=true
local steps=0
NeedFuel()
turtle.forward()
turtle.digDown()
turtle.down()
    while action  do
        local success, data = turtle.inspectDown()
        if success then
            if data.name~="minecraft:bedrock" then
            steps=steps+1
                    for i=1 , 4 do
                        turtle.dig()
                        turtle.forward()
                    end
                    for i=1 , 3 do
                        turtle.back()
                    end
                    turtle.digDown()
                    turtle.down()
            else action=false
            placeStairs(steps)
            end
    else action=false

        end
    end
end

function placeStairs(s)

turtle.select(2)
turtle.turnLeft()
turtle.turnLeft()
turtle.up()
turtle.placeDown()
for i=1 , s do
                        turtle.up()
                        turtle.forward()
                        turtle.placeDown()
end
turtle.forward()
end

function NeedFuel()
    if turtle.getFuelLevel() ~= "unlimited" and turtle.getFuelLevel() < 1  then

    turtle.select(1)
            if turtle.refuel() then
                print("Fuel level is: ", ( turtle.getFuelLevel() / turtle.getFuelLimit() ) * 100, "%")
            else
                print("Can't refuel ,Place some Coal in the 1st Slot")
            end
    else print("Fuel level is: ", ( turtle.getFuelLevel() / turtle.getFuelLimit() ) * 100, "%","We can still move", turtle.getFuelLevel(), "blocks")
end
end
digMyStairs()