Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Activate only when you Special Summon a "Gladiator Beast" monster. Your opponent discards 1 card of their choice.
--グラディアル・チェンジ
--Gladiator Lash
local s,id=GetID()
function s.initial_effect(c)
	--Activate
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCategory(CATEGORY_HANDES)
	e1:SetCode(EVENT_SPSUMMON_SUCCESS)
	e1:SetCondition(s.condition)
	e1:SetTarget(s.target)
	e1:SetOperation(s.activate)
	c:RegisterEffect(e1)
end
s.listed_series={SET_GLADIATOR}
function s.filter(c,tp)
	return c:IsFaceup() and c:IsControler(tp) and c:IsSetCard(SET_GLADIATOR)
end
function s.condition(e,tp,eg,ep,ev,re,r,rp)
	return eg:IsExists(s.filter,1,nil,tp)
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.GetFieldGroupCount(tp,0,LOCATION_HAND)>0 end
	Duel.SetOperationInfo(0,CATEGORY_HANDES,nil,0,tp,1)
end
function s.activate(e,tp,eg,ep,ev,re,r,rp)
	Duel.DiscardHand(1-tp,aux.TRUE,1,1,REASON_DISCARD|REASON_EFFECT)
end