No need to import os or string.  (Andrew Dalke & kjpylint)
diff --git a/Lib/shlex.py b/Lib/shlex.py
index 5b6a0ca..6eba4c8 100644
--- a/Lib/shlex.py
+++ b/Lib/shlex.py
@@ -1,6 +1,6 @@
 # Module and documentation by Eric S. Raymond, 21 Dec 1998 
 
-import sys, os, string
+import sys
 
 class shlex:
     "A lexical analyzer class for simple shell-like syntaxes."