🚀 go-pugleaf

I am trying to put a mark in the margin before some of the exercises in
my text.  But the LaTeX list mechanism is not letting me.

I've included a sample file below.  The first `\recommended' does as I
expected---it puts a pointer character in the left margin in line with
the exercise:
    |>  2) And this.
But the second _won't_ do this:
    |>  4)  (a) And this will ...
Instead it does this:
    |>  4)
          (a) And this will ...
Obviously I want the first (4) behavior.  Can someone help?

Thanks,
Jim Hefferon                  Math, St. Michael's College, Colchester, VT  USA
HEFFERON@SMCVAX.BITNET        (802) 654-2677
-----------------------------------------------------------------------------
\documentstyle{article}
% Recommended exercises are indicated by a marginal mark.
%  This is cobbed from TeXBook exercise 14.28
\def\recommended{\strut\vadjust{\kern-\strutdepth\specialmark}}
  \def\strutdepth{0.8ex}
  \def\specialmark{\vbox to \strutdepth{
    \baselineskip\strutdepth
    \vss\llap{\hbox to 2em{\hfil\recommendationmark}}\null}}
  \def\recommendationmark{\raise.25ex\hbox{$\rhd$}}

\begin{document}

\begin{center}
  Exercises
\end{center}
\begin{enumerate}
  \item Do this.
  \item \recommended And this.
  \item \begin{enumerate}
       \item This will take two steps.
       \item This is the second step.
    \end{enumerate}
  \item \recommended \begin{enumerate}
       \item And this will take two steps.
       \item Also this is the second step.
    \end{enumerate}
\end{enumerate}

\end{document}