code: public static function prefix(string $namespace, $subdomain = null, string $uri = null)
      {
          self::$namespace = $namespace;
          self::$subdomain = is_array($subdomain) ? $subdomain : [ $subdomain ];
          self::$uri = $uri;
      }
docs: Set namespace, subdomain and url prefixes for incoming routes.
  
  @static
  @param  string           $namespace namespace prefix
  @param  string|array     $subdomain subdomain prefix
  @param  string           $uri uri prefix