localmt=getmetatable(_G)or{}functionmt.__index(t,k)ifk~='arg'thenerror('Valor pas reconoguda '..tostring(k),2)endreturnnilendfunctionmt.__newindex(t,k,v)ifk~='arg'then--error('Valor pas reconoguda ' .. tostring(k), 2)endrawset(t,k,v)endsetmetatable(_G,mt)