local mt = getmetatable(_G) or {}function mt.__index (t, k) if k ~= 'arg' then error('Tried to read nil global ' .. tostring(k), 2) end return nilendfunction mt.__newindex(t, k, v) if k ~= 'arg' then error('Tried to write global ' .. tostring(k), 2) end rawset(t, k, v)endsetmetatable(_G, mt)