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

        <span class="comment">// is_unique is called to test whether this instance is the only </span>
        <span class="comment">// existing copy of a particular multi_pass</span>
        <span class="comment">//</span>
        <span class="comment">//   mp:    is a reference to the whole multi_pass instance</span>
        <span class="commen