pan class="op">)</span><span class="op">)</span>, 
            stat <span class="op">=</span> <span class="st">"stratum"</span>, 
            reverse <span class="op">=</span> <span class="cn">TRUE</span>, 
            size <span class="op">=</span> <span class="fu">rel</span><span class="op">(</span><span class="fl">3</span><span class="op">)</span><span class="op">)</span> <span class="op">+</span> 
  <span class="fu">theme_bw</span><span class="op">(</span><span class="op">)</span> <span class="op">+</sp