Clarify the description of the else clause for try/except, and add an
explanation of why you'd want to use it.
Based on a question from Michael Simcich <msimcich@accesstools.com>.
diff --git a/Doc/tut/tut.tex b/Doc/tut/tut.tex
index daae169..bdb5556 100644
--- a/Doc/tut/tut.tex
+++ b/Doc/tut/tut.tex
@@ -2996,9 +2996,9 @@
\end{verbatim}
The \keyword{try} \ldots\ \keyword{except} statement has an optional
-\emph{else clause}, which must follow all except clauses. It is
-useful to place code that must be executed if the try clause does not
-raise an exception. For example:
+\emph{else clause}, which, when present, must follow all except
+clauses. It is useful for code that must be executed if the try
+clause does not raise an exception. For example:
\begin{verbatim}
for arg in sys.argv[1:]:
@@ -3011,6 +3011,11 @@
f.close()
\end{verbatim}
+The use of the \keyword{else} clause is better than adding additional
+code to the \keyword{try} clause because it avoids accidentally
+catching an exception that wasn't raised by the code being protected
+by the \keyword{try} \ldots\ \keyword{except} statement.
+
When an exception occurs, it may have an associated value, also known as
the exceptions's \emph{argument}.