Fix some markup nits.
diff --git a/Doc/tut/tut.tex b/Doc/tut/tut.tex
index b227576..f79a183 100644
--- a/Doc/tut/tut.tex
+++ b/Doc/tut/tut.tex
@@ -1819,9 +1819,11 @@
0
\end{verbatim}
-Don't use this example's definition of \code{sum}: since summing numbers
-is such a common need, a built-in function \code{sum(\var{sequence})} is
-already provided, and works exactly like this\versionadded{2,3}.
+Don't use this example's definition of \function{sum()}: since summing
+numbers is such a common need, a built-in function
+\code{sum(\var{sequence})} is already provided, and works exactly like
+this.
+\versionadded{2.3}
\subsection{List Comprehensions}