Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
2 "lswarm" monsters While this card is in the Extra Monster Zone, if a monster would be Special Summoned from the Extra Deck to the Main Monster Zone, it must be Summoned in the zone this card points to. While this card points to a monster, neither player can target it with card effects, also it cannot be destroyed by battle or card effects. Once per turn, when a monster(s) on the field is destroyed by battle or by card effect: You can Special Summon Level 4 or lower "lswarm" monsters from your Deck in Defense Position, up to the number destroyed.
--インヴェルズ・オリジン
--Steelswarm Origin
--force effect scripted by edo9300
local ALL_EMZ=0x600060 --0x60 for your EMZs, 0x60<<16 for your opponent's EMZs
local s,id=GetID()
function s.initial_effect(c)
	--link summon
	Link.AddProcedure(c,aux.FilterBoolFunctionEx(Card.IsSetCard,SET_LSWARM),2,2)
	c:EnableReviveLimit()
	--force mzone
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetCode(EFFECT_FORCE_MZONE)
	e1:SetRange(LOCATION_EMZONE)
	e1:SetTargetRange(LOCATION_EXTRA,LOCATION_EXTRA)
	e1:SetValue(s.fmval)
	c:RegisterEffect(e1)
	--cannot be target/indestructable
	local e3=Effect.CreateEffect(c)
	e3:SetType(EFFECT_TYPE_SINGLE)
	e3:SetCode(EFFECT_CANNOT_BE_EFFECT_TARGET)
	e3:SetProperty(EFFECT_FLAG_SINGLE_RANGE)
	e3:SetRange(LOCATION_MZONE)
	e3:SetCondition(s.indcon)
	e3:SetValue(1)
	c:RegisterEffect(e3)
	local e4=e3:Clone()
	e4:SetCode(EFFECT_INDESTRUCTABLE_BATTLE)
	c:RegisterEffect(e4)
	local e5=e3:Clone()
	e5:SetCode(EFFECT_INDESTRUCTABLE_EFFECT)
	c:RegisterEffect(e5)
	--special summon
	local e6=Effect.CreateEffect(c)
	e6:SetDescription(aux.Stringid(id,0))
	e6:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e6:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_O)
	e6:SetCode(EVENT_DESTROYED)
	e6:SetRange(LOCATION_MZONE)
	e6:SetProperty(EFFECT_FLAG_DAMAGE_STEP)
	e6:SetCountLimit(1)
	e6:SetCondition(s.spcon)
	e6:SetTarget(s.sptg)
	e6:SetOperation(s.spop)
	c:RegisterEffect(e6)
end
s.listed_series={SET_LSWARM}
function s.fmval(e,c,fp,rp,r)
	return e:GetHandler():GetLinkedZone(rp)|ALL_EMZ
end
function s.indcon(e)
	return #(e:GetHandler():GetLinkedGroup():Filter(Card.IsMonster,nil))>0
end
function s.cfilter(c)
	return c:IsReason(REASON_BATTLE|REASON_EFFECT) and c:IsPreviousLocation(LOCATION_MZONE)
end
function s.spcon(e,tp,eg,ep,ev,re,r,rp)
	return eg:IsExists(s.cfilter,1,nil)
end
function s.spfilter(c,e,tp)
	return c:IsLevelBelow(4) and c:IsSetCard(SET_LSWARM) and c:IsCanBeSpecialSummoned(e,0,tp,false,false,POS_FACEUP_DEFENSE)
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and Duel.IsExistingMatchingCard(s.spfilter,tp,LOCATION_DECK,0,1,nil,e,tp) end
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,nil,1,tp,LOCATION_DECK)
end
function s.spop(e,tp,eg,ep,ev,re,r,rp)
	local ft=Duel.GetLocationCount(tp,LOCATION_MZONE)
	local ct=eg:FilterCount(s.cfilter,nil)
	ft=math.min(ft,ct)
	if ft<=0 then return end
	if Duel.IsPlayerAffectedByEffect(tp,CARD_BLUEEYES_SPIRIT) then ft=1 end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_SPSUMMON)
	local g=Duel.SelectMatchingCard(tp,s.spfilter,tp,LOCATION_DECK,0,1,ft,nil,e,tp)
	Duel.SpecialSummon(g,0,tp,tp,false,false,POS_FACEUP_DEFENSE)
end