code: public static function getRefererQueryParam($url, $key)
      {
          if (!$url) {
              return null;
          }
  
          $query = [];
  
          parse_str(parse_url($url, PHP_URL_QUERY), $query);
          if (isset($query[$key])) {
              return $query[$key];
          }
  
          return null;
      }
docs: Searches the url for a query parameter of a given key.
  @param string $url
  @param string $key
  @return mixed