public function setFormatOption($name, callable $handler)
    {
        if (in_array($name, static::$formatOptionsNames)) {
            return $this;
        }
        static::$formatOptionsNames[] = $name;
        static::$formatOptionsPlaceholders[] = '~' . count(static::$formatOptionsPlaceholders) . '~';
        static::$formatOptionsHandlers[] = $handler;
        return $this;
    }