diff --git a/hyperviewer/win32/sets.py b/hyperviewer/win32/sets.py
index 6ded7e7c88ac59a83db7e64530cfb8d58f986619..8af7eb75b43af747d9bbe61ca893e1d876000e0b 100755
--- a/hyperviewer/win32/sets.py
+++ b/hyperviewer/win32/sets.py
@@ -1,3 +1,6 @@
+# This file came from the /usr/local/lib/python2.3 directory in another distribution.
+# It was missing from the Windows Python 2.2.3 distribution.
+
 """Classes to represent arbitrary sets (including sets of sets).
 
 This module implements sets using dictionaries whose values are