an>  x_title <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  x_title_wrap <span class="op">=</span> <span class="fl">50</span>,</span>
<span>  x_zero <span class="op">=</span> <span class="cn">TRUE</span>,</span>
<span>  x_zero_line <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  y_zero_mid <span class="op">=</span> <span class="cn">FALSE</span>,</span>
<span>  y_breaks_n <span class="op">=</span> <span class="fl">5</span>,</span>
<span>  y_expand <span class="o