Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Your opponent cannot target face-up WATER monsters for attacks, except this one. All WATER monsters you control gain 300 ATK.
--水精鱗－アビスラング
--Mermail Abysslung
local s,id=GetID()
function s.initial_effect(c)
	--at limit
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetCode(EFFECT_CANNOT_SELECT_BATTLE_TARGET)
	e1:SetRange(LOCATION_MZONE)
	e1:SetTargetRange(0,LOCATION_MZONE)
	e1:SetValue(s.atlimit)
	c:RegisterEffect(e1)
	--atkup
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetRange(LOCATION_MZONE)
	e2:SetTargetRange(LOCATION_MZONE,0)
	e2:SetCode(EFFECT_UPDATE_ATTACK)
	e2:SetTarget(aux.TargetBoolFunction(Card.IsAttribute,ATTRIBUTE_WATER))
	e2:SetValue(300)
	c:RegisterEffect(e2)
end
function s.atlimit(e,c)
	return c~=e:GetHandler() and c:IsFaceup() and c:IsAttribute(ATTRIBUTE_WATER)
end