Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
If your opponent controls 3 or more monsters, they cannot declare an attack.
--攻通規制
--Attraffic Control
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)
	--cannot attack
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_CANNOT_ATTACK_ANNOUNCE)
	e2:SetProperty(EFFECT_FLAG_PLAYER_TARGET)
	e2:SetRange(LOCATION_SZONE)
	e2:SetTargetRange(0,1)
	e2:SetCondition(s.atcon)
	c:RegisterEffect(e2)
end
function s.atcon(e)
	return Duel.GetFieldGroupCount(e:GetHandlerPlayer(),0,LOCATION_MZONE)>=3
end