Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
All your Level 3 or lower Sea Serpent monsters can attack directly. If this card is sent to the GY to activate a WATER monster's effect: Add 1 Sea Serpent monster from your Deck to your hand, except "Atlantean Dragoons".
--海皇の竜騎隊
--Atlantean Dragoons
local s,id=GetID()
function s.initial_effect(c)
	--Direct attack
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetCode(EFFECT_DIRECT_ATTACK)
	e1:SetRange(LOCATION_MZONE)
	e1:SetTargetRange(LOCATION_MZONE,0)
	e1:SetTarget(s.datg)
	c:RegisterEffect(e1)
	--Add from deck to hand
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetCategory(CATEGORY_TOHAND+CATEGORY_SEARCH)
	e2:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_F)
	e2:SetCode(EVENT_TO_GRAVE)
	e2:SetCondition(s.thcon)
	e2:SetTarget(s.thtg)
	e2:SetOperation(s.thop)
	c:RegisterEffect(e2)
end
s.listed_names={id}
function s.datg(e,c)
	return c:IsLevelBelow(3) and c:IsRace(RACE_SEASERPENT)
end
function s.thcon(e,tp,eg,ep,ev,re,r,rp)
	return e:GetHandler():IsReason(REASON_COST) and re:IsActivated() and re:IsMonsterEffect()
		and re:GetHandler():IsAttribute(ATTRIBUTE_WATER)
end
function s.thfilter(c)
	return not c:IsCode(id) and c:IsRace(RACE_SEASERPENT) and c:IsAbleToHand()
end
function s.thtg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return true end
	Duel.SetOperationInfo(0,CATEGORY_TOHAND,nil,1,tp,LOCATION_DECK)
end
function s.thop(e,tp,eg,ep,ev,re,r,rp,c)
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_ATOHAND)
	local g=Duel.SelectMatchingCard(tp,s.thfilter,tp,LOCATION_DECK,0,1,1,nil)
	if #g>0 then
		Duel.SendtoHand(g,nil,REASON_EFFECT)
		Duel.ConfirmCards(1-tp,g)
	end
end