Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand) by controlling 2 or more face-up "X-Saber" monsters, and cannot be Special Summoned by other ways. Once per turn: You can target 1 Level 4 or lower "X-Saber" monster in your Graveyard; Special Summon that target.
--XX－セイバー フォルトロール
--XX-Saber Faultroll
local s,id=GetID()
function s.initial_effect(c)
	c:EnableReviveLimit()
	--cannot special summon
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetProperty(EFFECT_FLAG_CANNOT_DISABLE+EFFECT_FLAG_UNCOPYABLE)
	e1:SetCode(EFFECT_SPSUMMON_CONDITION)
	e1:SetValue(aux.FALSE)
	c:RegisterEffect(e1)
	--special summon
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_SPSUMMON_PROC)
	e2:SetProperty(EFFECT_FLAG_UNCOPYABLE)
	e2:SetRange(LOCATION_HAND)
	e2:SetCondition(s.spcon)
	c:RegisterEffect(e2)
	--special summon
	local e3=Effect.CreateEffect(c)
	e3:SetDescription(aux.Stringid(id,0))
	e3:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e3:SetType(EFFECT_TYPE_IGNITION)
	e3:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e3:SetRange(LOCATION_MZONE)
	e3:SetCountLimit(1)
	e3:SetTarget(s.target)
	e3:SetOperation(s.operation)
	c:RegisterEffect(e3)
end
s.listed_series={SET_X_SABER}
function s.spfilter(c)
	return c:IsFaceup() and c:IsSetCard(SET_X_SABER)
end
function s.spcon(e,c)
	if c==nil then return true end
	return Duel.GetLocationCount(c:GetControler(),LOCATION_MZONE)>0 and
		Duel.IsExistingMatchingCard(s.spfilter,c:GetControler(),LOCATION_MZONE,0,2,nil)
end
function s.filter(c,e,tp)
	return c:IsSetCard(SET_X_SABER) and c:IsLevelBelow(4) and c:IsCanBeSpecialSummoned(e,0,tp,false,false)
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsControler(tp) and chkc:IsLocation(LOCATION_GRAVE) and s.filter(chkc,e,tp) end
	if chk==0 then return Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and Duel.IsExistingTarget(s.filter,tp,LOCATION_GRAVE,0,1,nil,e,tp) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_SPSUMMON)
	local g=Duel.SelectTarget(tp,s.filter,tp,LOCATION_GRAVE,0,1,1,nil,e,tp)
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,g,1,0,0)
end
function s.operation(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc:IsRelateToEffect(e) then
		Duel.SpecialSummon(tc,0,tp,tp,false,false,POS_FACEUP)
	end
end