code: public function renderRequest()
      {
          $request = '';
          foreach ($this->displayVars as $name) {
              if (!empty($GLOBALS[$name])) {
                  $request .= '$' . $name . ' = ' . VarDumper::export($GLOBALS[$name]) . ";\n\n";
              }
          }
  
          return '<pre>' . rtrim($request, "\n") . '</pre>';
      }
docs: Renders the global variables of the request.
  List of global variables is defined in [[displayVars]].
  @return string the rendering result
  @see displayVars