unique</span><span class="special">&amp;);</span>

        <span class="comment">// clone is called whenever a multi_pass is copied</span>
        <span class="comment">//</span>
        <span class="comment">//   mp:    is a reference to the whole multi_pass instance</span>
        <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">MultiPass</span><span class="special">&gt;</span>
        <span class="keyword">static</span> 