t">//</span>
        <span class="comment">// The method is expected to return true if this instance is unique</span>
        <span class="comment">// (no other copies of this multi_pass exist).</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> <span class="keyword">bool</span> <span class="identifier">is_unique</span