Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
When an attack is declared involving your Warrior monster: You can Special Summon 1 Level 4 or lower Warrior monster from your hand. You can only use this effect of "Reinforcement of the Army's Troops" once per turn.
--増援部隊
--Reinforcement of the Army's Troops
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)
	--Special Summon from the hand
	local e2=Effect.CreateEffect(c)
	e2:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e2:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_O)
	e2:SetCode(EVENT_ATTACK_ANNOUNCE)
	e2:SetRange(LOCATION_SZONE)
	e2:SetCountLimit(1,id)
	e2:SetCondition(s.spcon)
	e2:SetTarget(s.sptg)
	e2:SetOperation(s.spop)
	c:RegisterEffect(e2)
end
function s.spcon(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetAttacker()
	if tc:IsControler(1-tp) then tc=Duel.GetAttackTarget() end
	return tc and tc:IsFaceup() and tc:IsControler(tp) and tc:IsRace(RACE_WARRIOR)
end
function s.filter(c,e,tp)
	return c:IsLevelBelow(4) and c:IsRace(RACE_WARRIOR) and c:IsCanBeSpecialSummoned(e,0,tp,false,false)
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and Duel.IsExistingMatchingCard(s.filter,tp,LOCATION_HAND,0,1,nil,e,tp) end
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,nil,1,tp,LOCATION_HAND)
end
function s.spop(e,tp,eg,ep,ev,re,r,rp)
	if Duel.GetLocationCount(tp,LOCATION_MZONE)<=0 then return end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_SPSUMMON)
	local g=Duel.SelectMatchingCard(tp,s.filter,tp,LOCATION_HAND,0,1,1,nil,e,tp)
	if #g>0 then
		Duel.SpecialSummon(g,0,tp,tp,false,false,POS_FACEUP)
	end
end