Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Target 1 face-up monster on the field and activate 1 of these effects; ● Increase that target's Level by 1. ● Reduce that target's Level by 1.
--スター・チェンジャー
--Star Changer
local s,id=GetID()
function s.initial_effect(c)
	--lv change
	local e1=Effect.CreateEffect(c)
	e1:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	e1:SetTarget(s.target)
	e1:SetOperation(s.operation)
	c:RegisterEffect(e1)
end
function s.filter(c)
	return c:IsFaceup() and c:IsLevelAbove(1)
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_MZONE) and s.filter(chkc) end
	if chk==0 then return Duel.IsExistingTarget(s.filter,tp,LOCATION_MZONE,LOCATION_MZONE,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_FACEUP)
	local g=Duel.SelectTarget(tp,s.filter,tp,LOCATION_MZONE,LOCATION_MZONE,1,1,nil)
	local tc=g:GetFirst()
	local op=0
	if tc:GetLevel()==1 then op=Duel.SelectOption(tp,aux.Stringid(id,0))
	else op=Duel.SelectOption(tp,aux.Stringid(id,0),aux.Stringid(id,1)) end
	e:SetLabel(op)
end
function s.operation(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	local tc=Duel.GetFirstTarget()
	if tc:IsFaceup() and tc:IsRelateToEffect(e) then
		local e1=Effect.CreateEffect(c)
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_UPDATE_LEVEL)
		e1:SetReset(RESET_EVENT|RESETS_STANDARD)
		if e:GetLabel()==0 then
			e1:SetValue(1)
		else e1:SetValue(-1) end
		tc:RegisterEffect(e1)
	end
end