r>
    <tr>
      <th>df</th>
      <td><p>Degrees of freedom of the spline basis. If this is specified but the knots parameter is NULL, then the appropriate number of internal knots
will be added at quantiles of the training data. If both df and knots are unspecified, the spline basis will have no internal knots.</p></td>
    </tr>
    <tr>
      <th>degree</th>
      <td><p>Specifies degree of spline basis used in the tree.</p></td>
    </tr>
    <tr>
      <th>intercept</th>
      <td><p>Specifies whethe