al_sets</a></code> and
        <code class="computeroutput"><a class="link" href="../../boost/icl/interval_map.html" title="Class template interval_map">interval_maps</a></code> can be
        filled and manipulated using set style operations such as union <code class="computeroutput"><span class="special">+=</span></code>, difference <code class="computeroutput"><span class="special">-=</span></code>
        and intersection <code class="computeroutput"><span class="special">&amp;=</span></code>.
      </p