r (<code>A*</code>) indicates zero or more occurrences
of <code>A</code>. The notation <code>A % B</code>, following the Boost Spirit
parser library’s notation, is shorthand for <code>?(A (B A)*)</code>, i.e.,
any number of <code>A</code> (including zero), separated by <code>B</code>. A
postfixed, curly-braced number indicates a fixed number of repetitions;
e.g., <code>A{6}</code> is equivalent to a sequence of six copies of <code>A</code>.</p>
</div>
<div id="programs" class="section level3 unnumbered">
