rloads (see below) are
      move aware and have overloads that look something like:
    </p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">B</span><span class="special">&gt;</span>
<span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">B</span><span class="special">,</span> <span class="identifier">et_off</span><span class="special">&gt;</span> <span clas