/ One single copy of value using T's copy constructor.</span>
    <span class="special">{</span><span class="special">}</span>

    <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">old</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">old_</span><span class="special">;</span> <span class=