code: public static function getStandardPort($scheme = null)
      {
          if ($scheme === null) {
              $scheme = self::getScheme();
          }
          if (isset(self::$schemes[$scheme])) {
              return self::$schemes[$scheme];
          }
          return 0;
      }
docs: Get standard port. If not found, then 0.
  
  @param string $scheme
  @return integer