diff -r 8ab8f5259f09 Lib/os.py
--- a/Lib/os.py	Wed Apr 27 23:13:46 2016 +0300
+++ b/Lib/os.py	Wed Apr 27 23:42:09 2016 -0400
@@ -320,10 +320,11 @@
     (e.g., via del or slice assignment), and walk will only recurse into the
     subdirectories whose names remain in dirnames; this can be used to prune the
     search, or to impose a specific order of visiting.  Modifying dirnames when
-    topdown is false is ineffective, since the directories in dirnames have
-    already been generated by the time dirnames itself is generated. No matter
-    the value of topdown, the list of subdirectories is retrieved before the
-    tuples for the directory and its subdirectories are generated.
+    topdown is false has no effect on the behavior of os.walk(), since the 
+    directories in dirnames have already been generated by the time dirnames 
+    itself is generated. No matter the value of topdown, the list of 
+    subdirectories is retrieved before the tuples for the directory and its 
+    subdirectories are generated.
 
     By default errors from the os.scandir() call are ignored.  If
     optional arg 'onerror' is specified, it should be a function; it