code: protected function encode()
      {
          $statements = array();
          foreach ($this->request as $pair) {
              if ($statement = $pair->asRequest()) {
                  $statements[] = $statement;
              }
          }
  
          return implode('&', $statements);
      }
docs: Renders the query string as a URL encoded request part.
  
  @return string        Part of URL.