Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
FLIP: Reveal all face-down cards on the field (Flip Effects are not activated), then return them to their original positions.
--厳格な老魔術師
--The Stern Mystic
local s,id=GetID()
function s.initial_effect(c)
	--Activate
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_FLIP)
	e1:SetTarget(s.target)
	e1:SetOperation(s.activate)
	c:RegisterEffect(e1)
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.IsExistingMatchingCard(Card.IsFacedown,tp,0,LOCATION_ONFIELD,1,nil) end
end
function s.activate(e,tp,eg,ep,ev,re,r,rp)
	local g=Duel.GetMatchingGroup(Card.IsFacedown,tp,0,LOCATION_ONFIELD,nil)
	if #g>0 then
		Duel.ConfirmCards(tp,g)
	end
end