Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Activate only if "Umi" is on the field. While "Umi" is on the field, you take no battle damage. If "Umi" is not on the field, destroy this card.
--竜巻海流壁
--Tornado Wall
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:SetCondition(s.umicheck)
	c:RegisterEffect(e1)
	--avoid battle damage
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_AVOID_BATTLE_DAMAGE)
	e2:SetRange(LOCATION_SZONE)
	e2:SetProperty(EFFECT_FLAG_PLAYER_TARGET)
	e2:SetTargetRange(1,0)
	e2:SetCondition(s.umicheck)
	c:RegisterEffect(e2)
	--self destroy
	local e3=Effect.CreateEffect(c)
	e3:SetType(EFFECT_TYPE_SINGLE)
	e3:SetProperty(EFFECT_FLAG_SINGLE_RANGE)
	e3:SetRange(LOCATION_SZONE)
	e3:SetCode(EFFECT_SELF_DESTROY)
	e3:SetCondition(aux.NOT(s.umicheck))
	c:RegisterEffect(e3)
end
s.listed_names={CARD_UMI}
function s.umicheck()
	return Duel.IsEnvironment(CARD_UMI)
end