Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Face-up Continuous Traps cannot be destroyed by battle or card effect, except "Imperial Custom". You can only control 1 "Imperial Custom".
--宮廷のしきたり
--Imperial Custom
local s,id=GetID()
function s.initial_effect(c)
	c:SetUniqueOnField(1,0,id)
	--Activate
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	c:RegisterEffect(e1)
	--Continuous traps cannot be destroyed by battle or card effects
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_INDESTRUCTABLE)
	e2:SetRange(LOCATION_SZONE)
	e2:SetTargetRange(LOCATION_ONFIELD,LOCATION_ONFIELD)
	e2:SetTarget(s.infilter)
	e2:SetValue(s.indesval)
	c:RegisterEffect(e2)
end
function s.infilter(e,c)
	return c:IsContinuousTrap() and c:GetCode()~=id
end
function s.indesval(e,re,r,rp)
	return (r&REASON_EFFECT+REASON_BATTLE)~=0
end