his library allows the template parameter <code class="computeroutput"><span class="identifier">T</span></code>
      to be of reference type: <code class="computeroutput"><span class="identifier">T</span><span class="special">&amp;</span></code>, and to some extent, <code class="computeroutput"><span class="identifier">T</span>
      <span class="keyword">const</span><span class="special">&amp;</span></code>.
    </p>
<p>
      However, since references are not real objects some restrictions apply and
    