Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
"Gazelle the King of Mythical Beasts" + "Berfomet" (This card is always treated as a "Phantom Beast" card.) When this card is destroyed: You can target 1 "Berfomet" or 1 "Gazelle the King of Mythical Beasts" in your GY; Special Summon that target.
--有翼幻獣キマイラ
--Chimera the Flying Mythical Beast
local s,id=GetID()
function s.initial_effect(c)
	--fusion material
	c:EnableReviveLimit()
	Fusion.AddProcMix(c,true,true,5818798,77207191)
	--Special summon
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_O)
	e1:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e1:SetProperty(EFFECT_FLAG_CARD_TARGET+EFFECT_FLAG_DAMAGE_STEP)
	e1:SetCode(EVENT_DESTROYED)
	e1:SetTarget(s.sptg)
	e1:SetOperation(s.spop)
	c:RegisterEffect(e1)
end
s.material_setcode=SET_PHANTOM_BEAST
function s.spfilter(c,e,tp)
	return c:IsCode(5818798,77207191) and c:IsCanBeSpecialSummoned(e,0,tp,false,false)
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_GRAVE) and chkc:IsControler(tp) and s.spfilter(chkc,e,tp) end
	if chk==0 then return Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and Duel.IsExistingTarget(s.spfilter,tp,LOCATION_GRAVE,0,1,nil,e,tp) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_SPSUMMON)
	local g=Duel.SelectTarget(tp,s.spfilter,tp,LOCATION_GRAVE,0,1,1,nil,e,tp)
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,g,1,0,0)
end
function s.spop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc and tc:IsRelateToEffect(e) then
		Duel.SpecialSummon(tc,0,tp,tp,false,false,POS_FACEUP)
	end
end