diff --git a/pep-0329.txt b/pep-0329.txt
index 76e65458e..e3779ce32 100644
--- a/pep-0329.txt
+++ b/pep-0329.txt
@@ -154,8 +154,9 @@ Here is a sample implementation for codetweaks.py::
         """
         import __builtin__
         env = vars(__builtin__).copy()
+        stoplist = dict.fromkeys(stoplist)
         if builtin_only:
-            stoplist.extend(f.func_globals)
+            stoplist.update(f.func_globals)
         else:
             env.update(f.func_globals)
 
@@ -214,19 +215,25 @@ Here is a sample implementation for codetweaks.py::
             elif type(v) in (type, ClassType):
                 bind_all(v, builtin_only, stoplist, verbose)
 
+
+    def f(): pass
+    try:
+        f.func_code.code                    
+    except AttributeError:                  # detect non-CPython environments
+        bind_all = lambda *args, **kwds: 0
+    del f
+
     import sys
     bind_all(sys.modules[__name__])         # Optimizer, optimize thyself!
 
-    
 
-The final code should have some minor embellishments:
+Note the automatic detection of a non-CPython environment that does not
+have bytecodes [3]_.  In that situation, the bind functions would simply
+return the original function unchanged.  This assures that the two
+line additions to library modules do not impact other implementations.
 
-* Automatic detection of a non-CPython environment that does not have
-  bytecodes [3]_.  In that situation, the bind functions would simply
-  return the original function unchanged.  This assures that the two
-  line additions to library modules do not impact other implementations.
+The final code should add a flag to make it easy to disable binding.
 
-* Add a flag to make it easy to disable binding.
 
 
 References