'>y_zero_line</span> <span class='kw'>=</span> <span class='kw'>NULL</span>,
  <span class='kw'>col_labels</span> <span class='kw'>=</span> <span class='kw'>NULL</span>,
  <span class='kw'>col_legend_ncol</span> <span class='kw'>=</span> <span class='kw'>NULL</span>,
  <span class='kw'>col_legend_nrow</span> <span class='kw'>=</span> <span class='kw'>NULL</span>,
  <span class='kw'>col_na</span> <span class='kw'>=</span> <span class='fl'>TRUE</span>,
  <span class='kw'>col_rev</span> <span class='kw'>=</spa