Neos\Flow\Http\Request::hasArgument PHP Method

    public function hasArgument($name)
    {
        return isset($this->arguments[$name]);
    }

 /**
  * Extracts the WidgetContext from the given $httpRequest.
  * If the request contains an argument "__widgetId" the context is fetched from the session (AjaxWidgetContextHolder).
  * Otherwise the argument "__widgetContext" is expected to contain the serialized WidgetContext (protected by a HMAC suffix)
  *
  * @param Request $httpRequest
  * @return WidgetContext
  */
 protected function extractWidgetContext(Request $httpRequest)
 {
     if ($httpRequest->hasArgument('__widgetId')) {
         return $this->ajaxWidgetContextHolder->get($httpRequest->getArgument('__widgetId'));
     } elseif ($httpRequest->hasArgument('__widgetContext')) {
         $serializedWidgetContextWithHmac = $httpRequest->getArgument('__widgetContext');
         $serializedWidgetContext = $this->hashService->validateAndStripHmac($serializedWidgetContextWithHmac);
         return unserialize(base64_decode($serializedWidgetContext));
     }
     return null;
 }