fier">Backend</span><span class="special">&gt;&amp;</span> <span class="identifier">b</span><span class="special">);</span>
</pre>
<p>
      Where the "unmentionable" return type is an implementation detail
      that, rather than containing the result of the multiplication, contains instructions
      on how to compute the result. In effect it's just a pair of references to the
      arguments of the function, plus some compile-time information that stores what
      the operation is.
    </p>
<p>
      Th