code: protected function findFormInFrame($page, $index, $method, $attribute)
      {
          $form = $this->frames[$index]->$method($attribute);
          if (isset($form)) {
              $form->setDefaultTarget($this->getPublicNameFromIndex($index));
          }
  
          return $form;
      }
docs: Finds a form in a page using a form finding method.
  Will also tag the form with the frame name it belongs in.
  
  @param SimplePage $page  Page content of frame.
  @param int $index    Internal frame representation.
  @param string $method    Method to use to find in a page.
  @param string $attribute Label, name or ID.
  
  @return SimpleForm       Form object containing the matching ID.