+% \DescribeMacro\skipanswer
+% The |\skipanswer| command is similar, but just skips over the answer rather
+% than writing it to the output file. It does nothing at all with counters
+% -- it's as if there was no answer given at all.
+%
+% It's OK to use commands like |\answer| and |\skipanswer| in your own
+% macros as long as they're the \emph{last} token. You can therefore say
+% something like
+%\begin{verbatim}
+%\newcommand{\evenanswer}{%
+% \ifthenelse%
+% {\isodd{\value{exercise}}}%
+% {\answer}%
+% {\skipanswer}%
+%}
+%\end{verbatim}
+% to get just the answers to the odd-numbered problems. (If you don't like
+% \package{ifthen} then you'll need to play with |\expandafter| for a bit.)
+%