luaL_getmetafield
if (!luaL_getmetafield(L, obj, event)) /* no metafield? */
LUALIB_API int (luaL_getmetafield) (lua_State *L, int obj, const char *e);
if (luaL_getmetafield(L, 1, "__metatable"))
if (!luaL_getmetafield(L, 1, method)) { /* no metamethod? */
luaL_getmetafield(L, 1, "__metatable");