Lua NPC Promotion to multiple promotions

[AncientAngelus]

Hello, I am requesting an npc like the king tibianus to be able to promote to a promotion to an x level for example 50 and then another promotion to a third promotion at x level lets say 100. I have the following code but not sure if this is good or not? I will appreciate any help. Thank you!

local keywordHandler = KeywordHandler:new()
local npcHandler = NpcHandler:new(keywordHandler)
NpcSystem.parseParameters(npcHandler)

function onCreatureAppear(cid)              npcHandler:onCreatureAppear(cid)            end
function onCreatureDisappear(cid)           npcHandler:onCreatureDisappear(cid)         end
function onCreatureSay(cid, type, msg)      npcHandler:onCreatureSay(cid, type, msg)    end
function onThink()                          npcHandler:onThink()                        end

local function creatureSayCallback(cid, type, msg)
    if not npcHandler:isFocused(cid) then
        return false
    end

local player = Player(cid)

if not player then
    return false
end

if player:getVocation() == 7 then
    local node1 = keywordHandler:addKeyword({'promote'}, StdModule.say, {npcHandler = npcHandler, onlyFocus = true, text = 'I can promote you for 20000 gold coins. Do you want to become a elite knight?'})
        node1:addChildKeyword({'yes'}, StdModule.promotePlayer, {npcHandler = npcHandler, cost = 20000, level = 50, text = 'Congratulations! You are now promoted.'})
        node1:addChildKeyword({'no'}, StdModule.say, {npcHandler = npcHandler, onlyFocus = true, text = 'Alright then, come back when you are ready.', reset = true})
elseif player:getVocation() == 15 then
    local node1 = keywordHandler:addKeyword({'second'}, StdModule.say, {npcHandler = npcHandler, onlyFocus = true, text = 'I can promote you for 20000 gold coins. Do you want me to promote you to super knight?'})
        node1:addChildKeyword({'yes'}, StdModule.promotePlayer, {npcHandler = npcHandler, cost = 20000, level = 300, text = 'Congratulations! You are now promoted.'})
        node1:addChildKeyword({'no'}, StdModule.say, {npcHandler = npcHandler, onlyFocus = true, text = 'Alright then, come back when you are ready.', reset = true})
end
end

npcHandler:setCallback(CALLBACK_MESSAGE_DEFAULT, creatureSayCallback)
npcHandler:addModule(FocusModule:new())