Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
This card can be treated as 2 Tributes for the Tribute Summon of an EARTH monster.
--トロイホース
--The Trojan Horse
local s,id=GetID()
function s.initial_effect(c)
	--double tribute
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetCode(EFFECT_DOUBLE_TRIBUTE)
	e1:SetValue(s.condition)
	c:RegisterEffect(e1)
end
function s.condition(e,c)
	return c:IsAttribute(ATTRIBUTE_EARTH)
end