Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Equip only to "Guardian Dreadscythe". It gains 500 ATK for each monster in the GYs.
--死神の大鎌－デスサイス
--Reaper Scythe - Dreadscythe
local s,id=GetID()
function s.initial_effect(c)
	aux.AddEquipProcedure(c,nil,aux.FilterBoolFunction(Card.IsCode,18175965))
	--atk
	local e3=Effect.CreateEffect(c)
	e3:SetType(EFFECT_TYPE_EQUIP)
	e3:SetCode(EFFECT_UPDATE_ATTACK)
	e3:SetValue(s.value)
	c:RegisterEffect(e3)
end
s.listed_names={18175965}
function s.value(e,c)
	return Duel.GetMatchingGroupCount(Card.IsMonster,0,LOCATION_GRAVE,LOCATION_GRAVE,nil)*500
end