="special">::</span><span class="identifier">reference</span> <span class="identifier">get_input</span><span class="special">(</span><span class="identifier">MultiPass</span><span class="special">&amp;</span> <span class="identifier">mp</span><span class="special">);</span>

        <span class="comment">// advance_input is called whenever the underlying input stream </span>
        <span class="comment">// should be advanced so that the next call to get_input will be </span>
        <span class="comment">/