    <td><p>TRUE or FALSE of whether to include x_var NA values. Defaults to TRUE.</p></td>
    </tr>
    <tr>
      <th>x_pretty_n</th>
      <td><p>For a numeric or date x variable, the desired number of intervals on the x scale, as calculated by the pretty algorithm. Defaults to 6.</p></td>
    </tr>
    <tr>
      <th>x_rev</th>
      <td><p>For a categorical variable, TRUE or FALSE of whether the x variable variable is reversed. Defaults to FALSE.</p></td>
    </tr>
    <tr>
      <th>x_title</th>
     