Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
While "Marshmallon" is in your Monster Zone, monsters your opponent controls can only target "Marshmallon" for attacks. * The above text is unofficial and describes the card's functionality in the OCG.
--マシュマロンのメガネ
--Marshmallon Glasses
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)
	c:RegisterEffect(e1)
	--
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_CANNOT_SELECT_BATTLE_TARGET)
	e2:SetRange(LOCATION_SZONE)
	e2:SetTargetRange(0,LOCATION_MZONE)
	e2:SetCondition(s.con)
	e2:SetValue(s.atlimit)
	c:RegisterEffect(e2)
end
s.listed_names={31305911}
function s.cfilter(c)
	return c:IsFaceup() and c:IsCode(31305911)
end
function s.con(e)
	return Duel.IsExistingMatchingCard(s.cfilter,e:GetHandlerPlayer(),LOCATION_MZONE,0,1,nil)
end
function s.atlimit(e,c)
	return c:IsFacedown() or c:GetCode()~=31305911
end