code: public function clickSubmitById($id, $additional = false)
      {
          if (! ($form = $this->page->getFormBySubmit(new SelectById($id)))) {
              return false;
          }
          $success = $this->load(
                  $form->getAction(),
                  $form->submitButton(new SelectById($id), $additional));
  
          return ($success ? $this->getContent() : $success);
      }
docs: Clicks the submit button by ID attribute of the button itself. The owning form will be
  submitted by this.
  
  @param string $id       Button ID.
  @param hash $additional Additional form data.
  
  @return string/boolean  Page on success.