Fix recent changes so that this section will format again.

Doc/lib/libdoctest.tex

@@ -406,18 +406,19 @@ often contrive doctest examples to produce numbers of that form:
 
 Simple fractions are also easier for people to understand, and that makes
 for better documentation.
-\end{enumerate}
 
 \item Be careful if you have code that must only execute once.
 
 If you have module-level code that must only execute once, a more foolproof
-definition of \function{_test} is
+definition of \function{_test()} is
 
 \begin{verbatim}
 def _test():
     import doctest, sys
     doctest.testmod(sys.modules["__main__"])
 \end{verbatim}
+\end{enumerate}
+
 
 \subsection{Soapbox}