code: public function form($form, $options = null, $as = 'searchform')
      {
          if (is_string($options)) {
              $as = $options;
              $options = null;
          }
  
          $this->stack['form'] = ['as' => $as, $form, $options];
          return $this;
      }
docs: Add arguments for the call to the SearchForm plugin.
  
  @see \Core\Controller\Plugin\SearchForm::get()
  
  @param        $elementsFieldset
  @param null   $buttonsFieldset
  @param string $as The name of the key in the result array.
  
  @return self