如何为Windows和Linux平台定义DIRECTORY_SEPARATOR？

if (!defined('DIRECTORY_SEPARATOR')) {
    define('DIRECTORY_SEPARATOR', PHP_OS == 'WINNT' ? '\\' : '/');
}

import os
DIRECTORY_SEPARATOR = os.path.sep

const DIRECTORY_SEPARATOR = process.platform === 'win32' ? '\\' : '/';

String DIRECTORY_SEPARATOR = System.getProperty("file.separator");

const string DIRECTORY_SEPARATOR = System.IO.Path.DirectorySeparatorChar.ToString();

DIRECTORY_SEPARATOR = File::ALT_SEPARATOR || File::SEPARATOR

package main

import (
	"fmt"
	"os"
	"path/filepath"
)

const DIRECTORY_SEPARATOR = string(os.PathSeparator)

func main() {
	fmt.Println(DIRECTORY_SEPARATOR)
}