f BOOST_VMD_RETURN_AFTER is in effect and an element is not found, either
        because the element number is out of range for the sequence or because filtering
        does not match the element type, a tuple will still be returned but both
        its elements will be empty.
      </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">vmd</span><span class="sp