Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Reduce the Levels of all monsters your opponent controls by 1.
--デビリアン・ソング
--Stygian Dirge
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:SetHintTiming(0,TIMINGS_CHECK_MONSTER)
	c:RegisterEffect(e1)
	--level
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_UPDATE_LEVEL)
	e2:SetRange(LOCATION_SZONE)
	e2:SetTargetRange(0,LOCATION_MZONE)
	e2:SetValue(-1)
	c:RegisterEffect(e2)
end