</span> <span class="keyword">operator</span><span class="special">&lt;</span><span class="special">(</span><a class="link" href="value_ref.html" title="Class template value_ref">value_ref</a><span class="special">&lt;</span> <span class="identifier">T1</span><span class="special">,</span> <span class="identifier">TagT1</span> <span class="special">&gt;</span> <span class="keyword">const</span> <span class="special">&amp;</span> left<span class="special">,</span> 
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