Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Until the End Phase, face-up Level 3 or lower WATER monsters you control cannot be destroyed by battle or by card effects.
--海竜神の加護
--Aegis of the Ocean Dragon Lord
local s,id=GetID()
function s.initial_effect(c)
	--Activate
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	e1:SetOperation(s.activate)
	c:RegisterEffect(e1)
end
function s.activate(e,tp,eg,ep,ev,re,r,rp)
	local e1=Effect.CreateEffect(e:GetHandler())
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetCode(EFFECT_INDESTRUCTABLE_BATTLE)
	e1:SetTarget(s.tg)
	e1:SetTargetRange(LOCATION_MZONE,0)
	e1:SetReset(RESET_PHASE|PHASE_END)
	e1:SetValue(1)
	Duel.RegisterEffect(e1,tp)
	local e2=Effect.CreateEffect(e:GetHandler())
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_INDESTRUCTABLE_EFFECT)
	e2:SetTarget(s.tg)
	e2:SetTargetRange(LOCATION_MZONE,0)
	e2:SetReset(RESET_PHASE|PHASE_END)
	e2:SetValue(1)
	Duel.RegisterEffect(e2,tp)
end
function s.tg(e,c)
	return c:IsLevelBelow(3) and c:IsAttribute(ATTRIBUTE_WATER)
end