SF patch #520382:  Expand shelve.py to have a full dictionary interface
and add a mixin to UserDict.py to make it easier to implement a full
dictionary interface.
diff --git a/Doc/lib/libshelve.tex b/Doc/lib/libshelve.tex
index 76eaaf4..1e02c7b 100644
--- a/Doc/lib/libshelve.tex
+++ b/Doc/lib/libshelve.tex
@@ -33,6 +33,10 @@
 d.close()       # close it
 \end{verbatim}
 
+In addition to the above, shelve supports all methods that are
+supported by dictionaries.  This eases the transition from dictionary
+based scripts to those requiring persistent storage.
+
 Restrictions:
 
 \begin{itemize}