Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
[ Pendulum Effect ] You cannot Pendulum Summon monsters, except "D/D" monsters. This effect cannot be negated. Once per turn, during your Standby Phase: Reduce this card's Pendulum Scale by 2 (min. 1), then destroy all monsters you control with a Level greater than or equal to this card's Pendulum Scale, except "D/D" monsters. ---------------------------------------- [ Monster Effect ] If this card is Normal or Special Summoned: You can activate 1 of these effects. You can only use this effect of "D/D Savant Kepler" once per turn. ● Target 1 other "D/D" card you control; return it to the hand. ● Add 1 "Dark Contract" card from your Deck to your hand.
--ＤＤ魔導賢者ケプラー
--D/D Savant Kepler
local s,id=GetID()
function s.initial_effect(c)
	--Pendulum Summon
	Pendulum.AddProcedure(c)
	--Cannot Pendulum Summon monsters, except "D/D" monsters
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetProperty(EFFECT_FLAG_PLAYER_TARGET+EFFECT_FLAG_CANNOT_DISABLE+EFFECT_FLAG_CANNOT_NEGATE)
	e1:SetCode(EFFECT_CANNOT_SPECIAL_SUMMON)
	e1:SetRange(LOCATION_PZONE)
	e1:SetTargetRange(1,0)
	e1:SetTarget(function(e,_c,tp,sumtp,sumpos) return not _c:IsSetCard(SET_DD) and (sumtp&SUMMON_TYPE_PENDULUM)==SUMMON_TYPE_PENDULUM end)
	c:RegisterEffect(e1)
	--Reduce this card's Pendulum Scale by 2
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetCategory(CATEGORY_DESTROY)
	e2:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_F)
	e2:SetCode(EVENT_PHASE|PHASE_STANDBY)
	e2:SetRange(LOCATION_PZONE)
	e2:SetCountLimit(1)
	e2:SetCondition(function(_,tp) return Duel.IsTurnPlayer(tp) end)
	e2:SetTarget(s.sctg)
	e2:SetOperation(s.scop)
	c:RegisterEffect(e2)
	--Activate 1 of these effects
	local e3=Effect.CreateEffect(c)
	e3:SetDescription(aux.Stringid(id,1))
	e3:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_O)
	e3:SetProperty(EFFECT_FLAG_DELAY)
	e3:SetCode(EVENT_SUMMON_SUCCESS)
	e3:SetCountLimit(1,id)
	e3:SetTarget(s.thtg)
	e3:SetOperation(s.thop)
	c:RegisterEffect(e3)
	local e4=e3:Clone()
	e4:SetCode(EVENT_SPSUMMON_SUCCESS)
	c:RegisterEffect(e4)
end
s.listed_series={SET_DD,SET_DARK_CONTRACT}
function s.desfilter(c,lvl)
	return c:IsFaceup() and not c:IsSetCard(SET_DD) and c:IsLevelAbove(lvl)
end
function s.sctg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return true end
	local scale=e:GetHandler():GetLeftScale()
	local lvl=math.max(1,scale-2)
	local g=Duel.GetMatchingGroup(s.desfilter,tp,LOCATION_MZONE,0,nil,lvl)
	if scale>1 then
		Duel.SetOperationInfo(0,CATEGORY_DESTROY,g,#g,0,0)
	end
end
function s.scop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	if c:GetLeftScale()<=1 then return end
	local g=Duel.GetMatchingGroup(s.desfilter,tp,LOCATION_MZONE,0,nil,c:GetLeftScale())
	if c:UpdateScale(-2)~=0 and #g>0 then
		Duel.BreakEffect()
		Duel.Destroy(g,REASON_EFFECT)
	end
end
function s.rthfilter(c)
	return c:IsFaceup() and c:IsSetCard(SET_DD) and c:IsAbleToHand()
end
function s.athfilter(c)
	return c:IsSetCard(SET_DARK_CONTRACT) and c:IsAbleToHand()
end
function s.thtg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	local c=e:GetHandler()
	if chkc then return chkc:IsOnField() and s.rthfilter(chkc) and chkc~=c end
	local b1=Duel.IsExistingTarget(s.rthfilter,tp,LOCATION_ONFIELD,0,1,c)
	local b2=Duel.IsExistingMatchingCard(s.athfilter,tp,LOCATION_DECK,0,1,nil)
	if chk==0 then return b1 or b2 end
	local op=Duel.SelectEffect(tp,
		{b1,aux.Stringid(id,2)},
		{b2,aux.Stringid(id,3)})
	e:SetLabel(op)
	if op==1 then
		e:SetCategory(CATEGORY_TOHAND)
		e:SetProperty(EFFECT_FLAG_CARD_TARGET+EFFECT_FLAG_DELAY)
		Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_RTOHAND)
		local g=Duel.SelectTarget(tp,s.rthfilter,tp,LOCATION_ONFIELD,0,1,1,c)
		Duel.SetOperationInfo(0,CATEGORY_TOHAND,g,1,0,0)
	else
		e:SetCategory(CATEGORY_TOHAND+CATEGORY_SEARCH)
		e:SetProperty(EFFECT_FLAG_DELAY)
		Duel.SetOperationInfo(0,CATEGORY_TOHAND,nil,1,tp,LOCATION_DECK)
	end
end
function s.thop(e,tp,eg,ep,ev,re,r,rp)
	if e:GetLabel()==1 then
		--Return 1 other "D/D" card you control to the hand
		local tc=Duel.GetFirstTarget()
		if tc:IsRelateToEffect(e) then
			Duel.SendtoHand(tc,nil,REASON_EFFECT)
			Duel.ConfirmCards(1-tp,tc)
		end
	else
		--Search 1 "Dark Contract" card
		Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_ATOHAND)
		local g=Duel.SelectMatchingCard(tp,s.athfilter,tp,LOCATION_DECK,0,1,1,nil)
		if #g>0 then
			Duel.SendtoHand(g,nil,REASON_EFFECT)
			Duel.ConfirmCards(1-tp,g)
		end
	end
end