Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
All "Gagaga" monsters you currently control gain 500 ATK for each "Gagaga" monster you currently control, until your next Standby Phase. You can only activate 1 "Gagagatag" per turn.
--ガガガタッグ
--Gagagatag
local s,id=GetID()
function s.initial_effect(c)
	--Activate
	local e1=Effect.CreateEffect(c)
	e1:SetCategory(CATEGORY_ATKCHANGE)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	e1:SetCountLimit(1,id,EFFECT_COUNT_CODE_OATH)
	e1:SetTarget(s.target)
	e1:SetOperation(s.activate)
	c:RegisterEffect(e1)
end
s.listed_series={SET_GAGAGA}
function s.target(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.IsExistingMatchingCard(aux.FaceupFilter(Card.IsSetCard,SET_GAGAGA),tp,LOCATION_MZONE,0,1,nil) end
end
function s.activate(e,tp,eg,ep,ev,re,r,rp)
	local sg=Duel.GetMatchingGroup(aux.FaceupFilter(Card.IsSetCard,SET_GAGAGA),tp,LOCATION_MZONE,0,nil)
	local atk=#sg*500
	local c=e:GetHandler()
	local tc=sg:GetFirst()
	for tc in aux.Next(sg) do
		local e1=Effect.CreateEffect(c)
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_UPDATE_ATTACK)
		e1:SetValue(atk)
		e1:SetReset(RESET_EVENT|RESETS_STANDARD|RESET_PHASE|PHASE_STANDBY,2)
		tc:RegisterEffect(e1)
	end
end