Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
This card cannot be Special Summoned. This card returns to its owner's hand during the End Phase of the turn it is Normal Summoned or flipped face-up. If this card battles a Synchro Monster, return both monsters to their owners' hands at the start of the Damage Step (without damage calculation).
--軍荼利
--Gundari
local s,id=GetID()
function s.initial_effect(c)
	Spirit.AddProcedure(c,EVENT_SUMMON_SUCCESS,EVENT_FLIP)
	--Cannot be Special Summoned
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetProperty(EFFECT_FLAG_CANNOT_DISABLE+EFFECT_FLAG_UNCOPYABLE)
	e1:SetCode(EFFECT_SPSUMMON_CONDITION)
	c:RegisterEffect(e1)
	--Return battling monsters to the hand
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetCategory(CATEGORY_TOHAND)
	e2:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_F)
	e2:SetCode(EVENT_BATTLE_START)
	e2:SetCondition(s.thcon)
	e2:SetTarget(s.thtg)
	e2:SetOperation(s.thop)
	c:RegisterEffect(e2)
end
function s.thcon(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	local bc=c:GetBattleTarget()
	return bc and bc:IsFaceup() and bc:IsType(TYPE_SYNCHRO)
end
function s.thtg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return true end
	local g=Group.FromCards(Duel.GetAttacker(),Duel.GetAttackTarget())
	Duel.SetOperationInfo(0,CATEGORY_TOHAND,g,#g,0,0)
end
function s.thop(e,tp,eg,ep,ev,re,r,rp)
	local g=Group.CreateGroup()
	local c=Duel.GetAttacker()
	if c:IsRelateToBattle() then g:AddCard(c) end
	local bc=Duel.GetAttackTarget()
	if bc and bc:IsRelateToBattle() then g:AddCard(bc) end
	if #g>0 then
		Duel.SendtoHand(g,nil,REASON_EFFECT)
	end
end