byeTree

        -- IDS
        sapplingId = "environmental:willow_sapling"
        logId = "environmental:willow_log"
        bonemealId = "minecraft:bone_meal"

        -- other settings
        count = 10        --max height turtle will go
        fuelBuffer =  50
        idleTime = 0.2
        maxSlotsFull = 15

        sappingSlot = 1
        logSlot = 2
        bonemealSlot = 12
        ---



        print("Make sure to put sappings in slot "..tostring(sappingSlot).." and logs in slot " .. tostring(logSlot) .. " and bonemal in slot "..tostring(bonemealSlot))

        function isCorrectItem(slot,name)
            turtle.select(slot)

            local id = turtle.getItemDetail() or "nothing"
            if id == "nothing" then
                    return "nothing"
            end

            i1 = id.name

            if i1 == name then
                return true
            else
                return false
            end
        end

        function ensureCorrectItem(slot,name,isOptional)
            local isCorrect = isCorrectItem(slot,name)

            function repond(itemName, slot)
                print("Incorrect items")
                print("Please insert"..itemName.." into "..tostring(slot) )
            end

            if isCorrect == true then
                return true -- tell caller all went well
            end

            if isOptional == true then
                -- check if slot has nothing
                if isCorrect == "nothing" then
                    return true --- tell caller all went well!
                end

                -- if it has something , check that it has bonemeal
                if isCorrect == false then
                    repond(name,slot)
                    write(" or empty it")

                    --- wait until something is in slot
                    while isCorrectItem(slot,name) == false do
                        sleep(2)
                        write(".")
                    end
                        return false -- tell caller to retry check
                end



                error("Something weird happened @ensureCorrectItem")

            else
                --check if slot has nothing
                if isCorrect == "nothing" then
                    respond(name,slot)
                    while isCorrectItem(slot,name) == false do
                        sleep(2)
                        write(".")
                    end
                    return false
                end

                --check if slot has the wrong item
                if isCorrect == false then
                    respond(name,slot)

                    while isCorrectItem(slot,name) == false do
                        sleep(2)
                        write(".")
                    end
                    return false
                end

                --return
                error("this should not have happened")
                return

            end



            error("Uknown error @ensureCorrectItem")

        end





        -- make sure a slot is as full as possible
        function combine(slot)
                ---Make sure slot is not already full
                turtle.select(slot)
                if turtle.getItemCount() == 64 then return end

                if turtle.getItemCount() > 0 then
                     for i=1,16 do
                            turtle.select(i)
                            if turtle.getItemCount() >0 then
                                if turtle.compareTo(i) then
                                        turtle.transferTo(slot)
                                end
                            end
                     end
                else
                    return "slot empty"
                end


        end

        -- see if there is tree left to dig up
        function isBlock()
            local fwd = turtle.detect()
            local up turtle.detectUp()
            if fwd == true then return true end
            if up == true then return true end
            return false
        end


        function main()
                --- do something repeatedly
                function rpt(func,count)
                                for i=1, count do
                                                func()
                                end
                end

                turtle.select(1)
                --- dig log then go up
                for i=1, count do
                                turtle.dig()
                                turtle.suck()
                                turtle.digUp()
                                turtle.suck()
                                turtle.up()
                        -- if no logs left, go back
                        if not isBlock() then
                            rpt(
                                function()
                                    turtle.down()
                                end, i
                            )
                            return
                        end

                end

                -- go back down if haven't already
                rpt(
                        turtle.down,
                        count
                )
        end




        isFullCounterMax = 10
        isFullCounter = 0   -- allows running only every n-th call
        function isFull(maxFull,force)
            isFullCounter = isFullCounter + 1

            if isFullCounter < isFullCounterMax and not force then return end

            isFullCounter = 0
            local c1 = combine(1)
            local c2 = combine(2)
            if c1=="slot empty" or c2 =="slot empty" then
                print("Please refill slots 1 and 2")
                while combine(1) == "slot empty" do
                    sleep(2)
                    write(".")
                end
                while combine(2) == "slot empty" do
                    sleep(2)
                    write(".")
                end

            end



            function returnIfEnough(slotsEmpty,slotsFull,maxEmpty,maxFull)
                --print("slots empty / max empty: "..tostring(slotsEmpty).."/"..tostring(maxEmpty))

                if slotsEmpty>=maxEmpty then
                    return false

                elseif slotsFull>=maxFull then
                    return true

                else
                    return nil

                end
            end

            --- --maxFull    = n
            local slotsEmpty = 0
            local slotsFull  = 0

            local maxEmpty = 17-maxFull
            for slot=1,16 do
                turtle.select(slot)
                local qtyInSlot = turtle.getItemCount()
                local isEmpty = qtyInSlot < 1

                if isEmpty then
                    slotsEmpty = slotsEmpty+1
                else
                    slotsFull = slotsFull+1
                end

                local enough = returnIfEnough(slotsEmpty,slotsFull,maxEmpty,maxFull)
                if enough ~= nil then return enough end
            end


            local enough = returnIfEnough(slotsEmpty,slotsFull,maxEmpty,maxFull)
            if enough ~= nil then return enough end

            error("unknown error @isFull")


        end

        function isTree()
                --is there a tree?
                local i1,i2 = turtle.inspect()
                local block = i2.name or "nothing"
                local affix = string.sub(block,-3,-1)

                if turtle.detect() and affix == "log" then
                        main()
                        turtle.select(1)
                        turtle.place()
                    --organise slotss

                end
        end

        while true do
                --make sure slots have correct items
                ensureCorrectItem(1,sapplingId,false)
                ensureCorrectItem(2,logId,false)
                ensureCorrectItem(bonemealSlot,bonemealId,true)

                -- if there's a tree, then dig it up
                isTree()

                --idle some
                sleep(idleTime )

                --refuel if neccesary and show fuel level
                local fuelSlot = 2
                local fuel = turtle.getFuelLevel()
                while turtle.getFuelLevel() < fuelBuffer do
                        turtle.select(fuelSlot)
                        turtle.refuel(1)
                        if turtle.getItemCount() <1 then
                                print("Please put more fuel into slot "..tostring(fuelSlot))
                                sleep(2)
                                while turtle.getItemCount() <1 do
                                    sleep(2)
                                    write(" .")
                                end
                        end
                end
                print(turtle.getFuelLevel())

             --Place a new sappling
             turtle.select(1)
             turtle.place()

             -- pickup left over items
             turtle.suck()
             turtle.suckUp()

            --Allow for bonemeal being used
            turtle.select(bonemealSlot)
            if turtle.getItemCount() > 0 then
                turtle.place()
            else
            end

            --Stop if full
            if isFull(maxSlotsFull) then
                print("Overfilled - please empty turtle to continue")

                while isFull(maxSlotsFull,true) do
                    sleep(2)
                    write(".")
                end


                print("resuming")
            end



        end