--- a/net/server_select.lua	Wed Jul 27 15:01:28 2016 +0100
+++ b/net/server_select.lua	Thu Jul 28 16:14:39 2016 +0800
@@ -31,7 +31,6 @@
 
 --// lua libs //--
 
-local os = use "os"
 local table = use "table"
 local string = use "string"
 local coroutine = use "coroutine"