Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
At the start of the Damage Step, if this card battles an opponent's monster: You can return both the opponent's monster and this card to the hand.
--N・グラン・モール
--Neo-Spacian Grand Mole
local s,id=GetID()
function s.initial_effect(c)
	--return to hand
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_TOHAND)
	e1:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_O)
	e1:SetCode(EVENT_BATTLE_START)
	e1:SetTarget(s.target)
	e1:SetOperation(s.operation)
	c:RegisterEffect(e1)
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk)
	local c=e:GetHandler()
	if chk==0 then return Duel.GetAttackTarget()==c or (Duel.GetAttacker()==c and Duel.GetAttackTarget()~=nil) end
	local g=Group.FromCards(Duel.GetAttacker(),Duel.GetAttackTarget())
	Duel.SetOperationInfo(0,CATEGORY_TOHAND,g,#g,0,0)
end
function s.operation(e,tp,eg,ep,ev,re,r,rp)
	local g=Group.CreateGroup()
	local c=Duel.GetAttacker()
	if c:IsRelateToBattle() then g:AddCard(c) end
	c=Duel.GetAttackTarget()
	if c~=nil and c:IsRelateToBattle() then g:AddCard(c) end
	if #g>0 then
		Duel.SendtoHand(g, nil, REASON_EFFECT)
	end
end